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Inherited metabolic diseases are rare and enzyme-dependent conditions, mostly passed on in an autosomal-recessive manner, and are based on genetic mutations. Each country has its own spectrum of diseases that can/must be tested before and/or after birth. Additionally to metabolic conditions, newborn screening programs might also include e.g., testing for other conditions like endocrine disorders, blood diseases, hearing loss, and/or cystic fibrosis. Out of the over 500 known diseases, 91 are currently treatable. The variety of possible diseases, their rarity, as well as the non-specific symptoms often pose a challenge for medical staff to make a diagnosis. Sensitization of the medical staff to the possible occurrence of such a disease is important. The geographical and ethical distribution can vary greatly. Therapy includes symptomatic treatment, changes in diet, as well as medical and/or interventional procedures. unfortunately, the diseases are mostly not curable, the therapy options are limited and therefore the overall quality of life is often reduced.

Treatment of many of the diseases in the panel of expanded newborn screening includes dietary therapy. Glutaric aciduria type 1 (GA1) is a hereditary disorder caused by mutations in the gene GCDH, encoding glutaryl‑CoA dehydrogenase, an enzyme in the amino acid metabolic pathways. The decreased activity of the enzyme leads to accumulation of neuro‑ toxic metabolites. The recommended treatment approaches for GA1 are the prescription of specialized nutrition products, levocarnitine, and symptomatic management. In 2021, clinical guidelines for the treatment of this rear disease were published in Russian Federation. To provide for the timely treatment, it is essential for a practitioner involved in the care patients with such a rare disorder as GA1 to have the knowledge of the principles of management, as well as practical algorithms for diet calculation.The article gives a detailed case‑based description of management during metabolic decompensation and the choice of dietary therapy for GA1 patients of different age groups.

Inherited metabolic diseases are a large group of inherited monogenic diseases. Metabolic disorders can cause child disability and mortality. Tandem mass spectrometry is a powerful technology that allows to diagnosis a large number of hereditary metabolic diseases. Clinical manifestations are variable, but more often the damages of nervous system, heart, liver, kidneys, hyperammonemia, hypo/hyperglycemia take place. The disease can make its debut at any age, but the severe forms of the disease manifest at infancy. Early diagnosis and treatment can significantly improve the prognosis; many countries expand the list of diseases included in screening programs. At the beginning of 2021 in most regions of the Russian Federation mass newborn screening is carried out for five hereditary metabolic diseases. The age and the range of clinical manifestation are variable; therefore, knowledge of this pathology is very important both for pediatricians and therapists, and for specialized doctors. The article presents a brief description of next groups of metabolic diseases: aminoacidopathies, organic acidurias and fatty acid oxidation defects.

Mitochondria—the intracellular powerhouse in which nutrients are converted into energy in the form of ATP or heat—are highly dynamic, double-membraned organelles that harness a plethora of cellular functions that sustain energy metabolism and homeostasis. Exciting new discoveries now indicate that the maintenance of this ever changing and functionally pleiotropic organelle is particularly relevant in terminally differentiated cells that are highly dependent on aerobic metabolism. Given the central role in maintaining metabolic and physiological homeostasis, dysregulation of the mitochondrial network might therefore confer a potentially devastating vulnerability to high-energy requiring cell types, contributing to a broad variety of hereditary and acquired diseases. In this Review, we highlight the biological functions of mitochondria-localized enzymes from the perspective of understanding—and potentially reversing—the pathophysiology of inherited disorders affecting the homeostasis of the mitochondrial network and cellular metabolism. Using methylmalonic acidemia as a paradigm of complex mitochondrial dysfunction, we discuss how mitochondrial directed-signaling circuitries govern the homeostasis and physiology of specialized cell types and how these may be disturbed in disease. This Review also provides a critical analysis of affected tissues, potential molecular mechanisms, and novel cellular and animal models of methylmalonic acidemia which are being used to develop new therapeutic options for this disease. These insights might ultimately lead to new therapeutics, not only for methylmalonic acidemia, but also for other currently intractable mitochondrial diseases, potentially transforming our ability to regulate homeostasis and health.

Objectives: The aim of this study was to gain a thorough understanding of parents’ perceptions of and experiences with the care networks surrounding young children (

(1) Background: Phenotypic diversity and long-term health outcomes of individuals with urea cycle disorders (UCDs) have been described in detail. However, there is limited information on the burden on affected families. (2) Methods: To evaluate the family burden in parents with children suffering from UCDs, we used validated questionnaires. Socio-demographic characteristics were evaluated, and an adapted version of the Parental Need Scale for Rare Diseases questionnaire was used. The survey was conducted in families of UCD patients cared for at the University Children’s Hospital Heidelberg. (3) Results: From April to November 2021, 59 participants were interviewed (mothers n = 34, fathers n = 25). The affected patients most frequently suffered from ornithine transcarbamylase deficiency (OTC-D) (female n = 12, male n = 12), followed by argininosuccinate synthetase deficiency (ASS-D, n = 13) and argininosuccinate lyase deficiency (ASL-D, n = 8). About one-third of the participants were “dissatisfied” or “extremely dissatisfied” with health professionals’ disease knowledge. In addition, 30% of the participants reported a medium or high need for “additional information on the development of their children”, and 44% reported a medium or high need “for information on available services”. A majority of 68% reported a need for additional support regarding services such as support groups (42%) or psychological counseling (29%). (4) Conclusions: Our study indicates that there is an unmet need for sufficient information about the development of children with UCDs, as well as for information about available support services for families with UCD patients. Furthermore, the results highlight the importance of establishing or improving family-centered care approaches. This pilot study may serve as a template for the assessment of the family burden associated with other inherited metabolic diseases.

The aim of the study was to develop a diagnostic model that allows with a high degree of probability predicting the development of inherited metabolic disease (IMD) in newborns with the hyperammonemia syndrome at the onset of disease and determine the adequate management tactics for such patients. Materials and Methods. The study included 15 female and 5 male infants with the hyperammonemia syndrome. All the patients underwent a full range of clinical laboratory studies in accordance with the standards of treatment of the underlying disease. Blood ammonia measuring (quantitative assessment) was carried out on the basis of the biochemical laboratory of the Children’s City Clinical Hospital No.1 (Nizhny Novgorod, Russia) using a portable PocketChem BA blood ammonia meter (Japan) and Ammonia Test Kit II test strips (Japan) in accordance with the manufacturer’s protocol. The confirmation of the IMD diagnosis was carried out using the tandem mass spectrometry (TMS) method and molecular genetic testing (genome sequencing). To check the assumptions, all the patients during the follow-up were randomized retrospectively into two groups depending on the TMS results and molecular genetic testing. Group 1 (n=8) included the patients diagnosed with IMD and group 2 (n=12) included the patients with transient hyperammonemia in the neonatal period. Results. The clinical manifestations of the hyperammonemia syndrome in the neonatal period are most frequently realized in the form of a syndrome of CNS depression of varying degrees up to coma (75%), a convulsive syndrome (55%), vomiting (40%) without significant differences in the frequency of occurrence due to the causes of hyperammonemia. In a third of cases, the onset of the hyperammonemia syndrome occurs in the early neonatal period. The ammonia levels in patients with hyperammonemia caused by IMD are statistically significantly higher than those in patients with transient hyperammonemia (p=0.014) which may serve as the first diagnostic sign of IMD in a newborn. A tendency to a more frequent development of anemia in infants with IMD (p=0.084) has been established which might be due to the compensation of metabolic acidosis. The presence of anemia in combination with clinical features and the level of hyperammonemia increases the risk of IMD. In the course of the study, a diagnostic model was developed for predicting the risk of IMD development in a newborn at the onset of hyperammonemia. Through the discriminant analysis, a statistically significant relationship was established between the level of ammonia at the onset, blood glucose and base deficiency levels, blood lactate, hemoglobin, erythrocyte levels, the average volume of erythrocytes and the pH level (p=0.040) with the risk of IMD development. The sensitivity of the model has amounted to 87.5%, the specificity — 83.3%. The diagnostic efficiency of the model is 85.0%. Conclusion. The proposed model can be used at detecting the debut of the hyperammonemia syndrome in newborns in order to predict the probability of IMD and work out the adequate tactics of the management for these patients.

Isobutyryl-CoA dehydrogenase deficiency (IBDHD, MIM: #611283) is a rare autosomal recessive hereditary disease, which is caused by genetic mutations of acyl-CoA dehydrogenase (ACAD) 8 and associated with valine catabolism. Here, tandem mass spectrometry (MS/MS) was applied to screen 302,993 neonates for inherited metabolic diseases (IMD) in Ningbo of China from 2017 to 2020. The results suggest that 198 newborns (0.7‰) were initially screened positive for IBDHD with C4-Carnitine, and 27 cases (0.1‰) were re-screened positive. Genetic diagnosis was performed on 21 of the 27 cases. Seven compound heterozygous variations, three biallelic variations, and one heterozygous variation of ACAD8 were found with a pathogenicity rate of 33.3% (7/21). In addition, seven biallelic variations, one heterozygous variation of acyl-CoA dehydrogenase short chain (ACADS), and one biallelic variation of acyl-CoA dehydrogenase short/branched chain (ACADSB) was detected. Further research showed that ACAD8 mutations of 11 IBDHD cases distributed in six different exons with total 14 mutation sites. Five of which were known suspected pathogenic sites (c.286G > A, c.553C > T, c.1000C > T, c.409G > A, c.500del) and six were novel mutation sites: c.911A > T, c.904C > T, c.826G > A, c.995T > C, c.1166G > A, c.1165C > T. This finding enriched the mutation spectrum of ACAD8 in IBDHD.

Cellular trafficking is essential to maintain critical biological functions. Mutations in 346 genes, most of them described in the last 5 years, are associated with disorders of cellular trafficking. Whereas initially restricted to membrane trafficking, the recent detection of many diseases has contributed to the discovery of new biological pathways. Accordingly, we propose to redesign this rapidly growing group of diseases combining biological mechanisms and clinical presentation into the following categories: (i) membrane trafficking (including organelle-related); (ii) membrane contact sites; (iii) autophagy; (iv) cytoskeleton-related. We present the most recently described pathophysiological findings, disorders and phenotypes. Although all tissues and organs are affected, the nervous system is especially vulnerable.

Understanding the genetic architecture of metabolic epilepsies is of paramount importance, both to current clinical practice and for the identification of further research directions. The main goals of our study were to identify the scope of metabolic epilepsies and to investigate their clinical presentation, diagnostic approaches and treatments. The International Classification of Inherited Metabolic Disorders and IEMbase were used as a basis for the identification and classification of metabolic epilepsies. Six hundred metabolic epilepsies have been identified, accounting for as much as 37% of all currently described inherited metabolic diseases (IMD). Epilepsy is a particularly common symptom in disorders of energy metabolism, congenital disorders of glycosylation, neurotransmitter disorders, disorders of the synaptic vesicle cycle and some other IMDs. Seizures in metabolic epilepsies may present variably, and most of these disorders are complex and multisystem. Abnormalities in routine laboratory tests and/or metabolic testing may be identified in 70% of all metabolic epilepsies, but in many cases they are non-specific. In total, 111 metabolic epilepsies (18% of all) have specific treatments that may significantly change health outcomes if diagnosed in time. Although metabolic epilepsies comprise an important and significant group of disorders, their real scope and frequency may have been underestimated.

Propionic Acidemia (PA) is a rare inherited metabolic disorder caused by the enzymatic block of propionyl-CoA carboxylase with the consequent accumulation of propionic acid, which is toxic for the brain and cardiac cells. Since a considerable amount of propionate is produced by intestinal bacteria, interest arose in the attempt to reduce propionate-producing bacteria through a monthly antibiotic treatment of metronidazole. In the present study, we investigated the gut microbiota structure of an infant diagnosed at 4 days of life through Expanded Newborn Screening (NBS) and treated the child following international guidelines with a special low-protein diet, specific medications and strict biochemical monitoring. Microbiota composition was assessed during the first month of life, and the presence of Bacteroides fragilis, known to be associated with propionate production, was effectively decreased by metronidazole treatment. After five antibiotic therapy cycles, at 4 months of age, the infant was supplemented with a daily mixture of three bifidobacterial strains, known not to be propionate producers. The supplementation increased the population of bifidobacteria, with Bifidobacterium breve as the dominating species; Ruminococcus gnavus, an acetate and formate producer, was also identified. Metabarcoding analysis, compared with low coverage whole metagenome sequencing, proved to capture all the microbial biodiversity and could be the elected tool for fast and cost-effective monitoring protocols to be implemented in the follow up of rare metabolic disorders such as PA. Data obtained could be a possible starting point to set up tailored microbiota modification treatment studies in the attempt to improve the quality of life of people affected by propionic acidemia.

Parents increasingly utilise the internet to obtain information on health practices, but the quality of online information about screening for inherited metabolic diseases (IMD) needs to be improved. A content analysis examined how IMD blood and urine tests were described online in local healthcare sectors between May and June 2021. Among the nine resources, four were blood test providers and five were urine test providers. All mentioned the test benefits and procedures. Other information, such as false-positive/negative or risk of pain, was infrequently mentioned. The descriptions of urine tests are advertised as outperforming blood tests and can be purchased from commercial laboratory sites without medical guidance. Two urine test providers claimed no false results were reported. A few commercial advertisements highlighted the simplicity of the urine test and potentially overstated the invasiveness of the blood test. We found that some advertisements described IMD as “silent killers” and emphasised the advantage of getting “reassurance” in controlling the child’s developmental health and well-being. To better protect the parents, or broadly, the public interest, regulatory and oversight measures on the urine tests should be implemented to promote the proper use of genetic tests. Without timely regulation and oversight, the incorrect descriptions might create a public misconception about utilising these commercial laboratory tests to inform health decisions.

Acute hepatic porphyria represents a rare, underdiagnosed group of inherited metabolic disorders due to hereditary defects of heme group biosynthesis pathway. Most patients have their definite diagnosis after several years of complex and disabling clinical manifestations and commonly after life-threatening acute neurovisceral episodes or severe motor handicap. Many key studies in the last two decades have been performed and led to the discovery of novel possible diagnostic and prognostic biomarkers and to the development of new therapeutic purposes, including small interfering RNA-based therapy, specifically driven to inhibit selectively delta-aminolevulinic acid synthase production and decrease the recurrence number of severe acute presentation for most patients. Several distinct mechanisms have been identified to contribute to the several neuromuscular signs and symptoms. This review article aims to present the current knowledge regarding the main pathophysiological mechanisms involved with the acute and chronic presentation of acute hepatic porphyria and to highlight the relevance of such content for clinical practice and in decision making about therapeutic options.

3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) Lyase deficiency (HMGLD) (OMIM 246450) is an autosomal recessive genetic disorder caused by homozygous or compound heterozygous variants in the HMGCL gene located on 1p36.11. Clinically, this disorder is characterized by a life-threatening metabolic intoxication with a presentation including severe hypoglycemia without ketosis, metabolic acidosis, hyper-ammoniemia, hepatomegaly and a coma. HMGLD clinical onset is within the first few months of life after a symptomatic free period. In nonacute periods, the treatment is based on a protein- and fat-restricted diet. L-carnitine supplementation is recommended. A late onset presentation has been described in very few cases, and only two adult cases have been reported. The present work aims to describe an incidental discovery of an HMGLD case in a 54-year-old patient and reports a comprehensive review of clinical and biological features in adult patients to raise awareness about the late-onset presentation of this disease.

BACKGROUND: Urea cycle disorders (UCD) are rare diseases that usually affect neonates or young children. During decompensations, hyperammonemia is neurotoxic, leading to severe symptoms and even coma and death if not treated rapidly. AIMS: Description of a cohort of patients with adult onset of UCDs. METHODS: Multicentric, retrospective and descriptive study of French adult patients with a diagnosis after 16 years of age of UCDs due to a deficiency in one of the 6 enzymes (arginase, ASL, ASS, CPS1, NAGS, OTC) or the two transporters (ORNT1 or citrin). RESULTS: Seventy-one patients were included (68% female, 32% male). The diagnosis was made in the context of (i) a metabolic decompensation (42%), (ii) family history (55%), or (iii) chronic symptoms (3%). The median age at diagnosis was 33 years (range 16-86). Eighty-nine percent of patients were diagnosed with OTC deficiency, 7% CPS1 deficiency, 3% HHH syndrome and 1% argininosuccinic aciduria. For those diagnosed during decompensations (including 23 OTC cases, mostly female), 89% required an admission in intensive care units. Seven deaths were attributed to UCD - 6 decompensations and 1 epilepsy secondary to inaugural decompensation. CONCLUSION: This is the largest cohort of UCDs diagnosed in adulthood, which confirms the triad of neurological, gastrointestinal and psychiatric symptoms during hyperammonemic decompensations. We stress that females with OTC deficiency can be symptomatic. With 10% of deaths in this cohort, UCDs in adults remain a life-threatening condition. Physicians working in adult care must be aware of late-onset presentations given the implications for patients and their families. This article is protected by copyright. All rights reserved.

In the last decade, the gene therapy (GT) field experienced a renaissance, thanks to crucial understandings and innovations in vector design, stem cell manipulation, conditioning protocols, and cell/vector delivery. These efforts were successfully coupled with unprecedented clinical results of the trials employing the newly developed technology and with the novel establishment of academic-industrial partnerships. A renewed and strengthened interest is rising in the development of gene-based approaches for inherited neurometabolic disorders with severe neurological involvement. Inherited metabolic disorders are monogenetic diseases caused by enzymatic or structural deficiencies affecting the lysosomal or peroxisomal metabolic activity. The metabolic defect can primarily affect the central nervous system, leading to neuronal death, microglial activation, inflammatory demyelination, and axonal degeneration. This review provides an overview of the GT strategies currently under clinical investigation for neurometabolic lysosomal and peroxisomal storage diseases, such as adrenoleukodystrophy and metachromatic leukodystrophy, as well as novel emerging indications such as mucopolysaccharidoses, gangliosidoses, and neuronal ceroid lipofuscinoses, with a comprehensive elucidation of the main features and mechanisms at the basis of a successful GT approach for these devastating diseases.

Background Following the broad application of new analytical methods, more and more pathophysiological processes in previously unknown diseases have been elucidated. The spectrum of clinical presentation of rare inherited metabolic diseases (IMDs) is broad and ranges from single organ involvement to multisystemic diseases. With the aim of overcoming the limited knowledge about the natural course, current diagnostic and therapeutic approaches, the project has established the first unified patient registry for IMDs that fully meets the requirements of the European Infrastructure for Rare Diseases (ERDRI). Results In collaboration with the European Reference Network for Rare Hereditary Metabolic Disorders (MetabERN), the Unified European registry for Inherited Metabolic Diseases (U-IMD) was established to collect patient data as an observational, non-interventional natural history study. Following the recommendations of the ERDRI the U-IMD registry uses common data elements to define the IMDs, report the clinical phenotype, describe the biochemical markers and to capture the drug treatment. Until today, more than 1100 IMD patients have been registered. Conclusion The U-IMD registry is the first observational, non-interventional patient registry that encompasses all known IMDs. Full semantic interoperability for other registries has been achieved, as demonstrated by the use of a minimum common core data set for equivalent description of metabolic patients in U-IMD and in the patient registry of the European Rare Kidney Disease Reference Network (ERKNet). In conclusion, the U-IMD registry will contribute to a better understanding of the long-term course of IMDs and improved patients care by understanding the natural disease course and by enabling an optimization of diagnostic and therapeutic strategies.

Inborn errors of metabolism (IEM) are inherited conditions caused by genetic defects in enzymes or cofactors. These defects result in a specific metabolic fingerprint in patient body fluids, showing accumulation of substrate or lack of an end-product of the defective enzymatic step. Untargeted metabolomics has evolved as a high throughput methodology offering a comprehensive readout of this metabolic fingerprint. This makes it a promising tool for diagnostic screening of IEM patients. However, the size and complexity of metabolomics data have posed a challenge in translating this avalanche of information into knowledge, particularly for clinical application. We have previously established next-generation metabolic screening (NGMS) as a metabolomics-based diagnostic tool for analyzing plasma of individual IEM-suspected patients. To fully exploit the clinical potential of NGMS, we present a computational pipeline to streamline the analysis of untargeted metabolomics data. This pipeline allows for time-efficient and reproducible data analysis, compatible with ISO:15189 accredited clinical diagnostics. The pipeline implements a combination of tools embedded in a workflow environment for large-scale clinical metabolomics data analysis. The accompanying graphical user interface aids end-users from a diagnostic laboratory for efficient data interpretation and reporting. We also demonstrate the application of this pipeline with a case study and discuss future prospects.

Summary We describe a case of a 21 years old woman affected by Citrullinemia type 1- Arginosuccinate Synthase deficiency (ASSD)-who underwent a SARS CoV2 infection during the first phase of pandemic burst in Italy. She had no symptoms of infection nor a metabolic crisis. After recovery from SARS CoV2, she experienced a worsening in their epilepsy despite therapy, with one/two crisis a week.

Background Inherited metabolic disorders (IMDs) are group of rare monogenic diseases, usually derived from reduced or absent activity in a single metabolic pathway. Most of the IMDs are inherited in an autosomal recessive manner. The incidence of IMDs varies from country to country and within different ethnic groups, but data is still scarce. Consanguinity rate among populations is highly contributor factor for IMDs incidence. There are no reports comparing the incidence of IMD in consanguineous and non-consanguineous populations from the same geographic region with the same diagnostic capabilities. Our study objective is to compare the incidence of IMDs between between the relatively low consanguineous Jewish population and the consanguineous Bedouin population, both living in the southern of Israel. Results During 1990–2017 there were 393,772 live births in the Negev district, of Southern of Israel. Among them 187,049 were of Jewish origin while 206,723 were of Bedouin-Muslim origin. A total of 223 children were diagnosed in this study period with IMDs. Among those 223 children with IMD, 33 were of Jewish origin while the other 190 children were of Bedouin-Muslim origin. The overall incidence for IMDs of the overall Negev population was 56.6/100,000 live birth. The incidence for IMD's among the Bedouin population was significantly higher than among Jewish population. Conclusions IMDs are extremely more common in the consanguineous Bedouin compared with the relatively non-consanguineous Jewish population of Southern Israel. Health policy makers should consider these data and prepare educational and genetic counselling problems accordingly.

In Italy, since 2016, extended neonatal screening has been mandatory throughout the country for about 40 inherited metabolic diseases. The law contains indications on: the list of pathologies, the information and consent, the methods of collecting and sending samples, the newborn screening system with the elements of its organization, appointed to guarantee the entire path of newborn screening, from the level I test to taking charge of the confirmed positive newborn, the communication and recall procedures for diagnostic confirmation and patient management, training and information initiatives, as well as the criteria for allocating the allocation. Extended neonatal screening has introduced new issues in diagnosis, choice of decision levels, and metabolic disease panels to screen. Of particular relevance in order to a strong reduction of false positives, was the introduction of the second-tier test for some diseases such as leucinosis, isovaleric acidemia, methylmalonic aciduria. As regards the diseases to be screened, the Italian situation differs greatly from what happens in Europe where in the majority of member states there is no legislation / law governing this preventive pediatric service; screening is almost always on a voluntary basis (with the collection of written informed consent from both parents) and applied on the basis of health guidelines or recommendations. In the world, the most complete panel is the US one (RUSP, Recommended Uniform Screening Panel) which currently contains 62 pathologies, 35 of which are defined as core panels and 27 as secondary panels. As the name implies, it is a panel that the US Health Resources and Services Administration -HRSA- recommends that it be applied by every State and that includes new screening in some areas including Pompe disease and MPS I, creatine deficiency. In conclusion, extended neonatal screening represents a real revolution in the metabolic field offering newborns an early diagnosis combined with effective therapeutic treatments capable of radically changing the course of these serious diseases.En Italia por ley, desde 2016, el cribado neonatal ampliado (SNE, Screening Neonatale Esteso) es obligatorio en todo el país para unas 40 enfermedades metabólicas hereditarias. La ley contiene indicaciones sobre: el listado de patologías, la información y consentimiento, los métodos de recolección y envío de muestras, el sistema de cribado neonatal con los elementos de su organización, el responsable de garantizar todo el proceso del cribado, desde la prueba de nivel 1 hasta hacerse cargo del recién nacido positivo confirmado, los procedimientos de comunicación y llamada para la confirmación diagnóstica y el manejo del paciente, las iniciativas de capacitación e información, así como los criterios de distribución del presupuesto. El cribado neonatal ampliado ha introducido nuevas cuestiones en el diagnóstico, la elección de los niveles de decisión y los paneles de enfermedades metabólicas que se deben cribar. De particular relevancia para una fuerte reducción de falsos positivos, fue la introducción de pruebas de segundo nivel para algunas enfermedades como leucinosis, acidemia isovalérica o aciduria metilmalónica, por ejemplo. En cuanto a las enfermedades a cribar, la situación italiana difiere mucho de lo que ocurre en Europa, donde en la mayoría de los estados miembros no existe una ley que regule este servicio pediátrico preventivo; el cribado casi siempre se realiza de forma voluntaria (con la obtención del consentimiento informado por escrito de ambos padres) y se aplica sobre la base de recomendaciones o directrices de salud. En el mundo, el panel más completo es el estadounidense (RUSP, Recommended Uniform Screening Panel) que actualmente contiene 62 patologías, 35 de las cuales se definen como panel principal y 27 como panel secundario. Como su nombre indica, es un panel que la Administración de Recursos y Servicios de Salud de EE.UU (US Health Resources and Services Administration –HRSA–) recomienda que sea aplicado en todos los estados y que incluye nuevos cribados en algunas áreas, como la enfermedad de Pompe y la enfermedad de Hurler-Scheie (MPS-I) o la deficiencia de creatina. En conclusión, el cribado neonatal ampliado representa una auténtica revolución en el campo metabólico ofreciendo al recién nacido un diagnóstico precoz combinado con tratamientos terapéuticos eficaces capaces de cambiar radicalmente el curso de estas graves enfermedades.

Background Inherited metabolic diseases (IMD) are complex medical conditions. Thanks to improvements in diagnosis and treatment, a growing number of pediatric IMD patients reach adulthood. Thus, clinical care of adults with IMD has emerged as a new and challenging reality. This purpose of this study of adults with IMD in an adult metabolic clinic at two academic hospitals (Lausanne and Geneva) was to help inform decisions on the future organization of health care for this group of patients. Methods All adult patients with a biochemical and/or genetic diagnosis of IMD followed at the clinics were included in the study. Electronic patient records were reviewed for clinical features, diagnostic studies, treatment and long-term outcome. Data of undiagnosed patients referred for suspected IMD were analyzed separately. Results 126 patients were included in the study. The most prevalent group of diseases was small molecules disorders with 82 (65%) patients, followed by energy defects disorders with 29 (23%) patients and complex molecules disorders with 15 (12%) patients. Overall, 64% of patients were diagnosed before, and 36% after the age 16 years. Among the 126 cases, 51% suffered from medical complications. 79% of the patients were receiving a specific treatment for their disease. Among the 138 undiagnosed patients referred for suspicion of IMD, investigations lead to a genetic diagnosis in 24 (17%) patients. 19 had confirmation of an IMD, 5 were found to have another genetic condition. Conclusions This retrospective study reveals significant features of adult IMD cohort. The disorders are heterogeneous, and there is no one-size-fits-all approach – treatment must be tailored to fit each specific disorder in each individual patient. Even patients who are followed at the dedicated clinic are not protected from metabolic decompensations and/or chronic organ-specific complications. While it is commonly assumed that patients with IMD are more stable once they become adults, our data show that the diseases continue to exact a lifelong toll. A coordinated monitoring of target organs by a multidisciplinary team is needed. To ensure that the success in diagnosis and treatment of individuals with IMD is sustained, there is a clear requirement for adequately staffed adult IMD clinics.

We surveyed individuals with inherited metabolic diseases (IMDs) or their caregivers to explore experiences with genetic testing. Pursuit of knowledge, benefit to science, clinician recommendations, cascade testing, and cost were important considerations for pursuing genetic testing. Knowledge about inheritance patterns was limited, even for those who had received genetic testing. Future studies should further examine knowledge of IMDs and genetic testing among families, and factors that impact clinicians' decisions to offer genetic testing for IMDs.

Background: Progressive intellectual and neurological deterioration (PIND) is a rare but severe childhood disorder characterized by loss of intellectual or developmental abilities, and requires quick diagnosis to ensure timely treatment to prevent possible irreversible neurological damage. Inborn errors of metabolism (IEMs) constitute a group of more than 1,000 monogenic conditions in which the impairment of a biochemical pathway is intrinsic to the pathophysiology of the disease, resulting in either accumulation of toxic metabolites and/or shortage of energy and building blocks for the cells. Many IEMs are amenable to treatment with the potential to improve outcomes. With this literature review we aim to create an overview of IEMs presenting with PIND in children, to aid clinicians in accelerating the diagnostic process. Methods: We performed a PubMed search on IEMs presenting with PIND in individuals aged 0–18 years. We applied stringent selection criteria and subsequently derived information on encoding genes, pathways, clinical and biochemical signs and diagnostic tests from IEMbase (www.iembase.org) and other sources. Results: The PubMed search resulted in a total of 2,152 articles and a review of references added another 19 articles. After applying our selection criteria, a total of 85 IEMs presenting with PIND remained, of which 57 IEMs were reported in multiple unrelated cases and 28 in single families. For 44 IEMs (52%) diagnosis can be achieved through generally accessible metabolic blood and urine screening tests; the remainder requires enzymatic and/or genetic testing. Treatment targeting the underlying pathophysiology is available for 35 IEMs (41%). All treatment strategies are reported to achieve stabilization of deterioration, and a subset improved seizure control and/or neurodevelopment. Conclusions: We present the first comprehensive overview of IEMs presenting with PIND, and provide a structured approach to diagnosis and overview of treatability. Clearly IEMs constitute the largest group of genetic PIND conditions and have the advantage of detectable biomarkers as well as amenability to treatment. Thus, the clinician should keep IEMs at the forefront of the diagnostic workup of a child with PIND. With the ongoing discovery of new IEMs, expanded phenotypes, and novel treatment strategies, continuous updates to this work will be required.

Background Inborn errors of metabolism (IEM) represent a subclass of rare inherited diseases caused by a wide range of defects in metabolic enzymes or their regulation. Of over a thousand characterized IEMs, only about half are understood at the molecular level, and overall the development of treatment and management strategies has proved challenging. An overview of the changing landscape of therapeutic approaches is helpful in assessing strategic patterns in the approach to therapy, but the information is scattered throughout the literature and public data resources. Results We gathered data on therapeutic strategies for 300 diseases into the Drug Database for Inborn Errors of Metabolism (DDIEM). Therapeutic approaches, including both successful and ineffective treatments, were manually classified by their mechanisms of action using a new ontology. Conclusions We present a manually curated, ontologically formalized knowledgebase of drugs, therapeutic procedures, and mitigated phenotypes. DDIEM is freely available through a web interface and for download at http://ddiem.phenomebrowser.net.

BACKGROUND: Laboratory investigations of cerebrospinal fluid (CSF) are essential when suspecting an inborn error of metabolism (IEM) involving neurological features. Available tests are currently performed on different analytical platforms, requiring a large sample volume and long turnaround time, which often delays timely diagnosis. Therefore, it would be preferable to have an "one-instrument" targeted multi-metabolite approach. METHOD: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform, based on two different methods for analysing 38 metabolites using positive and negative electrospray ionisation modes, was established. To allow for platform extension, both methods were designed to use the same CSF sample preparation procedure and to be run on the same separation column (ACE C18-PFP). RESULTS: Assessment of the LC-MS/MS platform methods was first made by analytical validation, followed by the establishment of literature-based CSF cut-off values and reference ranges, and by the measurement of available samples obtained from patients with confirmed diagnoses of aromatic l-amino acid decarboxylase deficiency, guanidinoacetate methyltransferase deficiency, ornithine aminotransferase deficiency, cerebral folate deficiency and methylenetetrahydrofolate reductase deficiency. CONCLUSION: An extendable targeted LC-MS/MS platform was developed for the analysis of multiple metabolites in CSF, thereby distinguishing samples from patients with IEM from non-IEM samples. Reference concentrations for several biomarkers in CSF are provided for the first time. By measurement on a single analytical platform, less sample volume is required (200 µL), diagnostic results are obtained faster, and preanalytical issues are reduced. SYNOPSIS: LC-MS/MS platform for CSF analysis consisting of two differentially designed methods.

Background The Canadian Inherited Metabolic Diseases Research Network (CIMDRN) is a pan-Canadian practice-based research network of 14 Hereditary Metabolic Disease Treatment Centres and over 50 investigators. CIMDRN aims to develop evidence to improve health outcomes for children with inherited metabolic diseases (IMD). We describe the development of our clinical data collection platform, discuss our data quality management plan, and present the findings to date from our data quality assessment, highlighting key lessons that can serve as a resource for future clinical research initiatives relating to rare diseases. Methods At participating centres, children born from 2006 to 2015 who were diagnosed with one of 31 targeted IMD were eligible to participate in CIMDRN’s clinical research stream. For all participants, we collected a minimum data set that includes information about demographics and diagnosis. For children with five prioritized IMD, we collected longitudinal data including interventions, clinical outcomes, and indicators of disease management. The data quality management plan included: design of user-friendly and intuitive clinical data collection forms; validation measures at point of data entry, designed to minimize data entry errors; regular communications with each CIMDRN site; and routine review of aggregate data. Results As of June 2019, CIMDRN has enrolled 798 participants of whom 764 (96%) have complete minimum data set information. Results from our data quality assessment revealed that potential data quality issues were related to interpretation of definitions of some variables, participants who transferred care across institutions, and the organization of information within the patient charts (e.g., neuropsychological test results). Little information was missing regarding disease ascertainment and diagnosis (e.g., ascertainment method – 0% missing). Discussion Using several data quality management strategies, we have established a comprehensive clinical database that provides information about care and outcomes for Canadian children affected by IMD. We describe quality issues and lessons for consideration in future clinical research initiatives for rare diseases, including accurately accommodating different clinic workflows and balancing comprehensiveness of data collection with available resources. Integrating data collection within clinical care, leveraging electronic medical records, and implementing core outcome sets will be essential for achieving sustainability.

Purposes Hydrops fetalis is a life-threatening fetal condition, and 85% of all cases are classified as nonimmune hydrops fetalis (NIHF). Up to 15% of NIHF cases may be due to inborn errors of metabolism (IEM), but a large proportion of cases linked to metabolic disorders remains undiagnosed. This lack of diagnosis may be related to the limitations of conventional biological procedures, which involve sequential investigations and require multiple samples and steps. In addition, this approach is time consuming. We have developed a next-generation sequencing (NGS) panel to investigate metabolic causes of NIHF, ascites, and polyhydramnios associated to another fetal abnormality. Methods The hydrops fetalis (HydFet) panel was designed to cover the coding regions and flanking intronic sequences of 41 genes. A retrospective study of amniotic fluid samples from 40 subjects was conducted. A prospective study was subsequently initiated, and six samples were analyzed using the NGS panel. Results Five IEM diagnoses were made using the HydFet panel (Niemann-Pick type C (NPC), Barth syndrome, HNF1Β deficiency, GM1 gangliosidosis, and Gaucher disease). This analysis also allowed the identification of 8p sequence triplication in an additional case. Conclusion NGS combined with robust bioinformatics analyses is a useful tool for identifying the causative variants of NIHF. Subsequent functional characterization of the protein encoded by the altered gene and morphological studies may confirm the diagnosis. This paradigm shift allows a significant improvement of IEM diagnosis in NIHF.

Resumen: Introducción: El fallo hepático agudo (FHA) secundario a enfermedades metabólicas hereditarias (EMH) es una enfermedad grave infrecuente de mal pronóstico. La intervención temprana puede salvar vidas. Objetivo: Describir la presentación clínica, la investigación y la evolución de FHA asociado a EMH en niños pequeños. Material y métodos: Estudio retrospectivo realizado en una unidad terciaria de cuidados intensivos neonatales y pediátricos, por un período de 27 años. Se analizaron los registros médicos de todos los niños hasta 2 años de edad, hospitalizados por FHA y con etiología metabólica documentada. Resultados: De los 34 casos de ALF, 18 se asociaban a EMH: galactosemia (4), síndrome de depleción del ADN mitocondrial (SDM) (3), deficiencia de ornitina transcarbamilasa (3), defectos congénitos de la glucosilación (2), tirosinemia tipo 1 (2), deficiencia de 3-hidroxi-acil-CoA deshidrogenasa de cadena larga (1), intolerancia hereditaria a la fructosa (1), aciduria metilmalónica clásica (1) y citrulinemia tipo 1 (1). La edad mediana fue de 1,3 meses. En el 67% de los casos se había observado al menos un síntoma o signo indicativo de EMH con anterioridad (vómitos, fallo de medro, hipotonía o retraso del desarrollo). Los signos físicos más frecuentes en el momento del ingreso fueron: hepatomegalia (72%), ictericia (67%) y encefalopatía (44%). Los niveles analíticos pico fueron: razón internacional normalizada media, 4,5; lactato mediano, 5 mmol/L; bilirrubina media, 201 μmol/L; alanina aminotransferasa (ALT) mediana, 137 UI/L; y amonio mediano, 177 μmol/L. Un paciente fue remitido para trasplante de hígado en contexto de FHA (MSD). La tasa de mortalidad fue del 44%. Discusión: La identificación de EMH como causa frecuente de FHA permitió el uso de medidas terapéuticas específicas y un asesoramiento familiar apropiado. Sus manifestaciones clínicas particulares y niveles moderados de ALT y bilirrubina pueden llevar a sospechar esta condición. Abstract: Introduction: Pediatric acute liver failure (ALF) due to inherited metabolic diseases (IMD) is a rare life-threatening condition with a poor prognosis. Early intervention may be lifesaving. Objective: To describe clinical presentation, investigation and outcomes of ALF related to IMD in young children. Material and methods: Retrospective review of the medical records of children aged up to 24 months, admitted to a tertiary pediatric and neonatal Intensive Care Unit during a 27-year period, fulfilling the ALF criteria, with documented metabolic etiology. Results: From 34 ALF cases, 18 were related to IMD: galactosemia (4), mitochondrial DNA depletion syndrome (MDS) (3), ornithine transcarbamilase deficiency (3), congenital defects of glycosylation (2), tyrosinemia type 1 (2), long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (1), hereditary fructose intolerance (1), classic methylmalonic aciduria (1) and citrulinemia type 1 (1). The median age was 1.3 months. At least one previous suggestive sign/symptom of IMD (vomiting, failure to thrive, hypotonia or developmental delay) was observed in 67% of the cases. The most common physical signs at admission included: hepatomegaly (72%), jaundice (67%) and encephalopathy (44%). The peak laboratorial findings were: mean international normalizad ratio 4.5, median lactate 5 mmol/L, mean bilirubin 201 μmol/L, median alanine aminotransferase (ALT) 137 UI/L and median ammonia 177 μmol/L. One patient was submitted to liver transplant in ALF context (MSD). The mortality rate was 44%. Discussion: The identification of IMD as a frequent cause of ALF allowed specific therapeutic measures and adequate family counselling. Particular clinical features and moderated ALT and bilirubin levels can lead to its suspicion.

Inherited metabolic diseases account for about one third of pediatric patients with hepatomegaly, acute liver failure, cirrhosis or cholestasis. Specifically for pediatric acute liver failure, they account for 10-15% of cases, with a mortality of 22-65%. The percentage of acute liver failure caused by an inherited metabolic disease in children

Adult metabolic medicine (AMM) is an expanding medical subspecialty, due to the increasing number of adult patients with inherited metabolic diseases (IMD). However, a formal training and postgraduate education in this field is not available in the majority of countries. Existing adult metabolic specialists (AMS) come from many different backgrounds. The aim of this survey was to assess the state of play as regards education and training in AMM worldwide. Members of the Society for the Study of Inborn Error of Metabolism adult metabolic group (n = 89) were asked to take part in this survey. Forty‐two AMS (47.2%) from 18 different countries completed the questionnaire. The most common specialties were internal medicine (38.1%), endocrinology (26.2%), genetics (21.4%), and neurology (21.4%). Ninety‐five percent of respondents considered that practical clinical experience had contributed importantly for their professional development, while only 27% felt the same for formal academic education. The current state of available education and training was judged as generally poor or fair (73% of the respondents). The most suggested ways of improving education and training in AMM were: to facilitate international internships; to implement courses on adult‐IMD; and to create a formal academic education. The skills considered most important for AMS were: recognition of signs and symptoms of diseases, knowledge of the available treatments, and ability to perform a correct follow up. In conclusion, worldwide, current available education and training in AMM is considered inadequate. This survey emphasizes the need for development of new, formal training opportunities to improve knowledge, and competence in this rapidly expanding field.

Metabolic phenotyping is poised as a powerful and promising tool for biomarker discovery in inherited metabolic diseases. However, few studies applied this approach to mcopolysaccharidoses (MPS). Thus, this innovative functional approach may unveil comprehensive impairments in MPS biology. This study explores mcopolysaccharidosis VI (MPS VI) or Maroteaux&ndash, Lamy syndrome (OMIM #253200) which is an autosomal recessive lysosomal storage disease caused by the deficiency of arylsulfatase B enzyme. Urine samples were collected from 16 MPS VI patients and 66 healthy control individuals. Untargeted metabolomics analysis was applied using ultra-high-performance liquid chromatography combined with ion mobility and high-resolution mass spectrometry. Furthermore, dermatan sulfate, amino acids, carnitine, and acylcarnitine profiles were quantified using liquid chromatography coupled to tandem mass spectrometry. Univariate analysis and multivariate data modeling were used for integrative analysis and discriminant metabolites selection. Pathway analysis was done to unveil impaired metabolism. The study revealed significant differential biochemical patterns using multivariate data modeling. Pathway analysis revealed that several major amino acid pathways were dysregulated in MPS VI. Integrative analysis of targeted and untargeted metabolomics data with in silico results yielded arginine-proline, histidine, and glutathione metabolism being the most affected. This study is one of the first metabolic phenotyping studies of MPS VI. The findings might shed light on molecular understanding of MPS pathophysiology to develop further MPS studies to enhance diagnosis and treatments of this rare condition.

Most rare diseases (RD) are genetically based, occur with very different symptoms and may cause a different degree of disability, especially inborn errors of metabolism (IEM). The clinical transition process of a patient with a RD reaching adulthood aims to ensure uninterrupted, coordinated and psychologically-appropriate health care through multidisciplinary expert units (EU). The specialist in Internal Medicine has a central role, along with Nutrition and Dietetics, a specialized ECM laboratory, and other specialists (Neurology, Clinical Genetics, Pharmacy, Ophthalmology, Obstetrics, Psychiatry, Nursing, Social Work, with the support of pediatricians experienced in ECM). EU should organize the overall care, develop clinical guidelines for diagnosis, follow-up and treatment, adapt Pharmacy services, create patient registers, establish relationships with patients’ associations, develop a scientific training program, establish international partnerships, facilitate collaboration with the Pharmaceutical Industry and have its own research activity. La mayoría de las enfermedades raras (ER) son de base genética, cursan con síntomas muy diversos y a menudo ocasionan un grado variable de discapacidad, especialmente los errores congénitos del metabolismo (ECM). El proceso de transición clínica de un paciente con una ER que alcanza la edad adulta pretende garantizar una atención sanitaria ininterrumpida, coordinada y psicológicamente apropiada mediante unidades expertas (UE) multidisciplinares. El especialista en medicina interna tiene un papel central, junto a los de nutrición y dietética, laboratorio especializado en ECM y otros especialistas (neurología, genética clínica, farmacia, oftalmología, obstetricia, psiquiatría, enfermería, trabajo social, con el apoyo de pediatría experimentada en ECM). Las UE deberían organizar la asistencia, desarrollar guías clínicas de diagnóstico, seguimiento y tratamiento, adaptar los servicios de farmacia, crear un registro de pacientes, establecer relaciones con las asociaciones de pacientes, desarrollar un programa científico formativo, establecer colaboraciones internacionales, facilitar la colaboración con la industria farmacéutica y mantener una actividad investigadora propia.

Background The gangliosidoses are rare inherited diseases that result in pathologic accumulation of gangliosides in the central nervous system and other tissues, leading to severe and progressive neurological impairment and early death in the childhood forms. No treatments are currently approved for the gangliosidoses, and development of treatments is impaired by limited understanding of the natural history of these diseases. Objective The objective of this study is to improve understanding of the juvenile gangliosidoses phenotypes and the late-infantile phenotypic subtype. Methods Through a prospective natural history study of subjects with juvenile GM1- and GM2-gangliosidosis, a timeline of clinical changes was developed for the classic juvenile phenotypes and the late-infantile phenotypes and results of serial neurodevelopmental testing was analyzed. Results Several candidate ‘outcome measures’ were identified: changes in ambulation and verbalization skills, the communication domain from neurodevelopmental testing and the caregiver-reported socialization domain. Conclusions The most common symptoms leading caregivers to seek a genetic diagnosis were changes in ambulation and verbalization.

To determine the relation between sudden unexpected death in infancy （SUDI） or apparent lifethreatening events （ALTE） and inborn errors of metabolism （IMD）, we investigated clinical and biochemical features in patients presenting with SUDI or ALTE, who were diagnosed with having hidden IMD. Subjects were infants between aged from 2 days and 3 years, detected during the period between January 2004 and December 2014. The diagnosis of IMD was based on the findings of gas chromatography/mass spectrometry and/or tandem mass spectrometry. IMDs were detected in 3 of 239 （1.2%） patients with SUDI, and in 22 of 219 （10.0%） patients with ALTE. These patients had a history of some prodromal illness and/or abnormalities of routine laboratory tests. When a case with SUDI or ALTE is encountered at an emergency unit, it is essential to take detailed medical histories and to measure biochemistry tests including mass spectrometric analysis as well as genetic testing.

To evaluate vaccination coverage of children and adolescents with inborn errors of metabolism (IEMs) and the attitudes of their parents towards vaccination, the vaccination status of 128 patients with IEM and 128 age- and gender-matched healthy controls was established by consulting the official vaccination chart. In children with IEMs, compared with healthy controls, low vaccination rates and/or delays in administration were observed for pneumococcal conjugate, meningococcus C, measles, mumps, rubella, diphtheria-tetanus-pertussis-inactivated polio, Bacillus Calmette-Guerin, and influenza vaccines. Among the parents of IEM patients, vaccine schedule compliance was primarily driven by the doctors at the hospital's reference centres; among the parents of the healthy controls, compliance was driven by the primary care paediatricians. These results show that IEM patients demonstrate sub-optimal vaccination coverage. Further studies of the different vaccines in each IEM disorder and educational programmes aimed at physicians and parents to increase immunization coverage in these patients are urgently needed.

Low-protein diets (LPDs) are the main treatment for urea cycle disorders (UCDs) and organic acidemias (OAs). In most cases, LPDs start in childhood and must be continued into adulthood. The improved life expectancy of patients with UCDs and OAs raises the question of their consequences on nutritional status in adult subjects. As this topic has so far received little attention, we conducted a review of scientific studies that investigated the nutrient intake and nutritional status in adult patients with UCDs and branched chain organic acidemias (BCOAs) on LPD. Methods: The literature search was conducted in PubMed/MEDLINE, Scopus, EMBASE and Google Scholar from 1 January 2000 to 31 May 2020, focusing on nutrient intake and nutritional status in UCD and OA adult patients. Results: Despite protein restriction is recommended as the main treatment for UCDs and OAs, in these patients, protein intake ranges widely, with many patients who do not reach safety levels. When evaluated, micronutrient intake resulted below recommended values in some patients. Lean body mass resulted in most cases lower than normal range while fat body mass (FM) was often found normal or higher than the controls or reference values. Protein intake correlated inversely with FM both in adult and pediatric UCD patients. Conclusions: The clinical management of adult patients with UCDs and BCOAs should include an accurate assessment of the nutritional status and body composition. However, as little data is still available on this topic, further studies are needed to better clarify the effects of LPDs on nutritional status in adult UCD and BCOA patients.

Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorders associated with impaired glycosaminoglycans (GAGs) catabolism. In MPS I, II, III, and VII, heparan sulfate (HS) cannot be degraded because of the lack of sufficient activity of the respective enzymes, and its accumulation in the brain causes neurological symptoms. Globotriaosylsphingosine (LysoGb3), the deacylated form of globotriaosylceramide (Gb3), is described as a highly sensitive biomarker for another lysosomal storage disease&mdash, Fabry disease. The connection between MPSs and LysoGb3 has not yet been established. This study included 36&mdash, MPS I, 15&mdash, MPS II, 25&mdash, MPS III, 26&mdash, MPS IV, and 14&mdash, MPS VI patients who were diagnosed by biochemical and molecular methods and a control group of 250 males and 250 females. The concentration of lysosphingolipids (LysoSLs) was measured in dried blood spots by high pressure liquid chromatography&mdash, tandem mass spectrometry. We have demonstrated that LysoGb3 concentration was significantly elevated (p &lt, 0.0001) in untreated MPS I (3.07 + 1.55 ng/mL), MPS II (5.24 + 2.13 ng/mL), and MPS III (6.82 + 3.69 ng/mL) patients, compared to the control group (0.87 + 0.55 ng/mL). LysoGb3 level was normal in MPS VI and MPS IVA (1.26 + 0.39 and 0.99 + 0.38 ng/mL, respectively). Activity of &alpha, galactosidase A (&alpha, Gal A), an enzyme deficient in Fabry disease, was not, however, inhibited by heparan sulfate in vitro, indicating that an increase of LysoGb3 level in MPS I, MPS II, and MPS III is an indirect effect of stored MPSs rather than a direct result of impairment of degradation of this compound by HS. Our findings indicate some association of elevated LysoGb3 concentration with the neuronopathic forms of MPSs. The pathological mechanism of which is still to be studied.

Most rare diseases (RD) are genetically based, occur with very different symptoms and may cause a different degree of disability, especially inborn errors of metabolism (IEM). The clinical transition process of a patient with a RD reaching adulthood aims to ensure uninterrupted, coordinated and psychologically-appropriate health care through multidisciplinary expert units (EU). The specialist in Internal Medicine has a central role, along with Nutrition and Dietetics, a specialized ECM laboratory, and other specialists (Neurology, Clinical Genetics, Pharmacy, Ophthalmology, Obstetrics, Psychiatry, Nursing, Social Work, with the support of pediatricians experienced in ECM). EU should organize the overall care, develop clinical guidelines for diagnosis, follow-up and treatment, adapt Pharmacy services, create patient registers, establish relationships with patients’ associations, develop a scientific training program, establish international partnerships, facilitate collaboration with the Pharmaceutical Industry and have its own research activity., La mayoría de las enfermedades raras (ER) son de base genética, cursan con síntomas muy diversos y a menudo ocasionan un grado variable de discapacidad, especialmente los errores congénitos del metabolismo (ECM). El proceso de transición clínica de un paciente con una ER que alcanza la edad adulta pretende garantizar una atención sanitaria ininterrumpida, coordinada y psicológicamente apropiada mediante unidades expertas (UE) multidisciplinares. El especialista en medicina interna tiene un papel central, junto a los de nutrición y dietética, laboratorio especializado en ECM y otros especialistas (neurología, genética clínica, farmacia, oftalmología, obstetricia, psiquiatría, enfermería, trabajo social, con el apoyo de pediatría experimentada en ECM). Las UE deberían organizar la asistencia, desarrollar guías clínicas de diagnóstico, seguimiento y tratamiento, adaptar los servicios de farmacia, crear un registro de pacientes, establecer relaciones con las asociaciones de pacientes, desarrollar un programa científico formativo, establecer colaboraciones internacionales, facilitar la colaboración con la industria farmacéutica y mantener una actividad investigadora propia.

By facilitating timely diagnosis and treatment initiation, population-wide newborn screening programs have led to important reductions in morbidity and mortality for many rare diseases, including medium-chain acyl-CoA dehydrogenase (MCAD) deficiency and very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Newborn screening has also expanded the spectrum of disease severity for MCAD and VLCAD deficiencies to include a higher proportion of milder cases, raising questions about appropriate disease management. To date there has been no systematic attempt to characterize best management practices in terms of the guidance that is available to those who provide care for MCAD and VCLAD deficiencies; nor has there been an attempt to understand the extent to which current practices align with such currently available guidance. The two projects that are part of this thesis sought to address these research gaps with a particular focus on two key disease-specific management practices we identified in advance as priorities: the use of carnitine supplementation and the recommended duration of fasting. The objective of the first project was to systematically review the quality and content of clinical practice guidelines and/or recommendations for the diagnosis and management of both MCAD and VLCAD deficiencies. Two independent reviewers assessed the eligibility of citations retrieved from a comprehensive search of the peer-reviewed and grey literature. We appraised the quality of the reviewed guidance and extracted information on the content of recommendations. From the 25 guidance documents that met our inclusion criteria, only 7 incorporated evidence reviews, indicating that guidance in this field does not generally meet established methodological standards for the rigorous development of clinical practice guidelines. With respect to content, we identified unclear and inconsistent recommendations regarding fasting times and the use of carnitine supplementation. Further empirical evidence in these areas is necessary to inform the development of future rigorous guidelines. The objective of the second project was to identify actual practices in the management of MCAD deficiency. We conducted a scoping review of published literature on treatment practices around the world and a secondary analysis of data documenting treatments received by participants in a Canadian pediatric cohort study. For the scoping review, citations retrieved from our comprehensive search strategy were screened by two independent reviewers. We extracted information on study characteristics and disease management. Our secondary analysis included longitudinal data for Canadian children with MCAD deficiency, born between 2006 and 2015 and enrolled in a cohort study at one of 13 centres. For both project components, we described carnitine supplementation and fasting times, overall and according to potential indicators of disease severity (genotype, biochemical phenotype). We identified 5 relevant publications in the scoping review and analyzed data for 107 children participating in the Canadian cohort. Management practices related to carnitine supplementation and fasting times for MCAD deficiency were highly variable based on both data sources. There was some evidence of an association between genotype and carnitine use, which, based on the scoping review, may be due to a relationship between genotype and carnitine deficiency. While actual practice was in some ways aligned with the guidance we reviewed in the first project, these results underscore the need for further evidence to address areas of uncertainty that have been prioritized by patients and families, clinicians, and health researchers, including questions regarding the potential to tailor treatment to predicted disease severity and an emphasis on controversial therapies such as carnitine supplementation.

Copyright: The Authors in collaboration with the Canadian Inherited Metabolic Diseases Research Network (CIMDRN). Background: We describe early health services utilization for children diagnosed with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency through newborn screening in Ontario, Canada, relative to a screen negative comparison cohort. Methods: Eligible children were identified via newborn screening between April 1, 2006 and March 31, 2010. Age-stratified rates of physician encounters, emergency department (ED) visits and inpatient hospitalizations to March 31, 2012 were compared using incidence rate ratios (IRR) and incidence rate differences (IRD). We used negative binomial regression to adjust IRRs for sex, gestational age, birth weight, socioeconomic status and rural/urban residence. Results: Throughout the first few years of life, children with MCAD deficiency (n = 40) experienced statistically significantly higher rates of physician encounters, ED visits, and hospital stays compared with the screen negative cohort. The highest rates of ED visits and hospitalizations in the MCAD deficiency cohort occurred from 6 months to 2 years of age (ED use: 2.1–2.5 visits per child per year; hospitalization: 0.5–0.6 visits per child per year), after which rates gradually declined. Conclusions: This study confirms that young children with MCAD deficiency use health services more frequently than the general population throughout the first few years of life. Rates of service use in this population gradually diminish after 24 months of age. This study was funded through a Canadian Institutes of Health Research (CIHR) Emerging Team Grant (TR3–119195). Maria Karaceper received a graduate scholarship through a charitable donation to the Children’s Hospital of Eastern Ontario. Dr. Mitchell receives research support from the Dr. Eleanor Mackenzie Harpur Pediatric Endowment Fund.

Purpose: Recognizing individuals with inherited diseases can be difficult because signs and symptoms often overlap those of common medical conditions. Focusing on inborn errors of metabolism (IEMs), we present a method that brings the knowledge of highly specialized experts to professionals involved in early diagnoses. We introduce IEMbase, an online expert-curated IEM knowledge base combined with a prototype diagnosis support (mini-expert) system. Methods: Disease-characterizing profiles of specific biochemical markers and clinical symptoms were extracted from an expert-compiled IEM database. A mini-expert system algorithm was developed using cosine similarity and semantic similarity. The system was evaluated using 190 retrospective cases with established diagnoses, collected from 15 different metabolic centers. Results: IEMbase provides 530 well-defined IEM profiles and matches a user-provided phenotypic profile to a list of candidate diagnoses/genes. The mini-expert system matched 62% of the retrospective cases to the exact diagnosis and 86% of the cases to a correct diagnosis within the top five candidates. The use of biochemical features in IEM annotations resulted in 41% more exact phenotype matches than clinical features alone. Conclusion: IEMbase offers a central IEM knowledge repository for many genetic diagnostic centers and clinical communities seeking support in the diagnosis of IEMs

Timely newborn screening and genetic profiling are crucial in early recognition and treatment of inborn errors of metabolism (IEMs). A proposed nosology of IEMs has inserted 1,015 well-characterized IEMs causing alterations in specific metabolic pathways. With the increasing expansion of metabolomics in clinical biochemistry and laboratory medicine communities, several research groups have focused their interest on the analysis of metabolites and their interconnections in IEMs. Metabolomics has the potential to extend metabolic information, thus allowing to achieve an accurate diagnosis for the individual patient and to discover novel IEMs. Structural and functional information on 247 metabolites associated with 147 IEMs and 202 metabolic pathways involved in various IEMs have been reported in the human metabolome data base (HMDB). For each metabolic gene, a new computational approach can be developed for predicting a set of metabolites, whose concentration is predicted to change after gene knockout in urine, blood and other biological fluids. Both targeted and untargeted mass spectrometry (MS)-based metabolomic approaches have been used to expand the range of disease-associate metabolites. The quantitative targeted approach, in conjunction with chemometrics, can be considered a basic tool for validating known diagnostic biomarkers in various metabolic disorders. The untargeted approach broadens the identification of new biomarkers in known IEMs and allows pathways analysis. Urine is an ideal biological fluid for metabolomics in neonatology; however, the lack of standardization of preanalytical phase may generate potential interferences in metabolomic studies. The integration of genomic and metabolomic data represents the current challenge for improving diagnosis and prognostication of IEMs. The goals consist in identifying both metabolically active loci and genes relevant to a disease phenotype, which means deriving disease-specific biological insights.

Background Inherited metabolic diseases (IMD) are a large group of rare single-gene disorders that are typically diagnosed early in life. There are important evidence gaps related to the comparative effectiveness of therapies for IMD, which are in part due to challenges in conducting randomized controlled trials (RCTs) for rare diseases. Registry-based RCTs present a unique opportunity to address these challenges provided the registries implement standardized collection of outcomes that are important to patients and their caregivers and to clinical providers and healthcare systems. Currently there is no core outcome set (COS) for studies evaluating interventions for paediatric IMD. This protocol outlines a study that will establish COS for each of two relatively common IMD in children, phenylketonuria (PKU) and medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. Methods This two-part study is registered with the Core Outcome Measures in Effectiveness Trials (COMET) initiative. Part 1 includes a rapid review and development of an evidence map to identify a comprehensive listing of outcomes reported in past studies of PKU and MCAD deficiency. The review follows established methods for knowledge synthesis, including a comprehensive search strategy, two stages of screening citations against inclusion/exclusion criteria by two reviewers working independently, and extraction of important data elements from eligible studies, including details of the outcomes collected and outcome measurement instruments. The review findings will inform part 2 of our study, a set of Delphi surveys to establish consensus on the highest priority outcomes for each condition. Healthcare providers, families of children with PKU or MCAD deficiency, and health system decision-makers will be invited to participate in two to three rounds of Delphi surveys. The design of the surveys will involve parents of children with IMD who are part of a family advisory forum. Discussion This protocol is a crucial step in developing the capacity to launch RCTs with meaningful outcomes that address comparative effectiveness questions in the field of paediatric IMD. Such trials will contribute high-quality evidence to inform decision-making by patients and their family members, clinicians, and policy-makers. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-2327-3) contains supplementary material, which is available to authorized users.

Myoclonus is a manifestation of many neurological diseases, by differing in etiology and pathogenesis. The high prevalence of myoclonus in children with cardinally different prognoses of diseases of not only the nervous system, but also other organs and systems causes to resume investigations into myoclonus as a syndrome, to specify its terminology and classification, to improve diagnostic criteria, and to optimize additional diagnostic schemes.

Background: Molecular diagnosis of glycogen storage diseases (GSDs) is important to enable accurate diagnoses and make appropriate therapeutic plans. The aim of this study was to evaluate the PHKA2 mutation spectrum in Korean patients with GSD type IX. Methods: Thirteen Korean patients were tested for PHKA2 mutations using direct sequencing and a multiplex polymerase chain reaction method. A comprehensive review of the literature on previously reported PHKA2 mutations in other ethnic populations was conducted for comparison. Results: Among 13 patients tested, six unrelated male patients with GSD IX aged 2 to 6 years at the first diagnostic work-up for hepatomegaly with elevated aspartate transaminase (AST) and alanine transaminase (ALT) were found to have PHKA2 mutations. These patients had different PHKA2 mutations: five were known mutations (c.537 + 5G > A, c.884G > A [p.Arg295His], c.3210_3212delGAG [p.Arg1072del], exon 8 deletion, and exons 27-33 deletion) and one was a novel mutation (exons 18-33 deletion). Notably, the most common type of mutation was gross deletion, in contrast to other ethnic populations in which the most common mutation type was sequence variant. Conclusions: This study expands our knowledge of the PHKA2 mutation spectrum of GSD IX. Considering the PHKA2 mutation spectrum in Korean patients with GSD IX, molecular diagnostic methods for deletions should be conducted in conjunction with direct sequence analysis to enable accurate molecular diagnosis of this disease in the Korean population.

Theoretical and experimental evidence has shown that protein function, regulation and degradation are intrinsically linked to the dynamic and fluctuating nature of protein ensembles. However, the effect of missense mutations on catalytic performance are often interpreted from conformational analyses derived from X-ray crystallography, molecular dynamics and modeling, while effects on conformational fluctuations at the active site as the source of catalytic defects are rarely investigated. Here, we explore the role of conformational fluctuations in the catalytic efficiency of WT and three missense mutations in the UDP-galactose 4′-epimerase (GALE) protein causing type III galactosemia. Using comprehensive molecular dynamics simulations and small angle X-ray scattering we correlate low NAD+ binding affinity in some mutants with an increased population of non-competent conformations for NAD+ binding. Proteolysis studies combined with thermodynamic calculations reveal that mutations affecting GALE catalytic performance favor larger conformational fluctuations at the N-terminal domain and NAD+ binding site, shifting the equilibrium towards non-binding competent states in the native ensemble. Therefore, we provide a novel ensemble-based thermodynamic mechanism to explain catalytic defects caused by missense mutations that links large and transient conformational fluctuations and loss of catalytic efficiency and substrate/coenzyme affinity. In the context of this mechanism, we propose that allosteric ligands aimed at modulating these transient conformational fluctuations might correct catalytic defects in inherited metabolic diseases, representing a different approach to current small ligand therapies which target the low stability, but not catalytic defects, of mutations., This work was supported by grants from MINECO (BIO2015-66426-R, CSD2009-00088) and Junta de Andaluc´ıa (P11-CTS-07187). A. L. P. was supported by a Ram´on y Cajal research contract from MINECO/University of Granada (RYC-2009-04147).

Neurological involvement is a typical feature of several inherited metabolic diseases. The onset of signs and/or symptoms may appear as early as the first days of life or after an interval of normal or near-normal growth and development. Metabolic decomposition usually presents with a severe clinical phenotype, which include poor feeding, vomiting, lethargy, seizures, and loss of consciousness. This spectrum of manifestations is often fatal; however, severe neurological sequelae and/or regression of neurodevelopmental milestones can be the prominent signs in those who survive. Overall, treatable inborn errors of metabolism can be divided in three groups, namely: (Group 1) inborn errors of intermediary metabolism giving rise to acute or chronic intoxication; (Group 2) inborn errors of intermediary metabolism affect in genergetic processes; and (Group 3) inborn errors involving cellular organelles, including lysosomal, peroxisomal, glycosylation, and cholesterol synthesis defects. The spectrum of neurological manifestations includes developmental delay, seizures and epilepsy, pyramidal and extrapyramidal signs, movement disorders, vision and hearing impairment, peripheral neuropathy, and psychiatric abnormalities. The main anatomical/imaging patterns reflects selective vulnerability of nervous system substance and include atrophy, (predominantly) symmetrical abnormalities, and dysmyelination, As several patients with neurometabolic diseases responds favorably to therapeutic trials, early detection and early intervention is of utmost importance to prevent catabolic-related damage and to revert to normal or near-normal parameters neurodevelopmental milestones.