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Objectives: Patients with inherited metabolic disorders (IMDs) may require emergency hospital care to prevent life-threatening situations such as metabolic decompensation. To date, over one thousand different rare IMDs have been identified, which means that healthcare professionals (HCPs) initiating emergency treatment may not be familiar with these conditions. The objective of this initiative was to provide HCPs with practical guidance for the acute management of children and adults with IMDs who need emergency care, regardless of the underlying reason., Methods: We outline how a multidisciplinary working group from the French IMDs Healthcare Network for Rare Diseases, known as G2M, has created concise and standardized protocols _each consisting of a single double-sided A4 sheet _ focused on a specific disease, a group of diseases, or a particular symptom. Prior to validation, these protocols were reviewed by all French reference and competence centres for IMDs, as well as by medical experts from other specialities when necessary, physicians from emergency and intensive care units, and representatives from patient associations., Results and Conclusion: In total, 51 emergency protocols containing essential information have been developed and provided to affected patients. All the emergency protocols are freely available in both French and English at https://www.filiere-g2m.fr/urgences. These standardized protocols aim to enhance the emergency care of patients without delay, while also assisting HCPs by increasing their confidence and efficiency, minimizing the risk of dosage errors when administering specialized treatments, saving time, and reducing the number of phone calls to metabolic medicine specialists on night duty. The protocols are scheduled for annual review to facilitate further improvements based on feedback from HCPs and patients, as well as to accommodate any changes in management practices as they evolve., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest related to the content of this manuscript. Within the past 36 months, outside of the submitted work: Juliette Bouchereau reports support for attending a meeting from Ultragenyx; Karine Mention reports a research contract with Sanofi, fees for lectures from Sanofi and Chiesi, and participation in a Board for Chiesi; Jérémy Do Cao reports support for attending a meeting and fees for a presentation at this meeting, both from Sanofi Rare Diseases; Aline Cano reports fees for presentations from Sanofi and Genzyme, honorarium for participation in a Scientific Board from Sanofi, and medical writing fees from Nutricia; Célia Hoebeke reports registration and presentation fees from BioMarin for a meeting, registration fees from Sanofi Aventis France, and a meal offered by Orphalan during another meeting; Anaïs Brassier reports fees for lectures from Sanofi and BioMarin, support for attending meetings from Sanofi, and participation in an Advisory Board for Sanofi; Laurent Gouya reports having participated for free in a Scientific Committee for Alnylam Pharmaceuticals and in the IPNET Executive Board, and having been Chairman of the GenOmics Committee of Foundation For Rare Diseases (FFRD, Fondation Maladies Rares); Jean-Baptiste Arnoux reports fees for lectures from Sanofi and Recordati, consulting fees from Sobi, Immedica pharma and Zealand pharma, and support for attending meetings from Immedica pharma; Cécile Acquaviva-Bourdain reports consulting fees from Alnylam Pharmaceuticals, Ultragenix, and Novodordisk, and fees for lectures from Alnylam Pharmaceuticals; Pierre Broué reports payments to the institution that employs him from Mirium Pharma, and personal fees for Advisory Boards from Mirum Pharma and Albireo AB; Claire Douillard reports grants from Sanofi and Ultragenyx, fees for a presentation from Alnylam Pharmaceuticals, and support for attending a meeting from Sanofi., (Copyright © 2024. Published by Elsevier Inc.)

NEW DEVELOPMENTS IN NEONATAL SCREENING. The French national newborn screening program (NBS) celebrated its 50th anniversary in 2022. A few drops of blood are drawn between 48 and 72 hours of life for each newborn on a filter paper and entrusted to a Regional Center for Newborn Screening, which analyses it diligently. When the result is beyond a threshold, the baby and its parents are summoned to a specialized paediatric department. If the suspected disease is confirmed, specific care can be started in time to avoid or limit a disability. Each year, nearly 1.000 sick children are diagnosed by NBS in France, and treated in a specialized hospital team. The 2018 National Rare Disease Plan has relaunched the NBS process. Until then, 7 diseases whose hearing loss were detected. Since then, 7 other diseases have been added to the program, and others were recommended or are being assessed, opening a new page in the history of NBS in France., Competing Interests: D. Cheillan déclare des interventions ponctuelles pour Orchard Therapeutics. M. Polak, T. Nguyen-Khoa, S. Lachambre, P de Lonlay, A. Khemiri et S. Courapied déclarent n’avoir aucun lien d’intérêts. J.-B. Arnoux déclare des interventions ponctuelles pour Ultragenyx, Rezolute, Immedica et Biomarin, et avoir été pris en charge, à l’occasion de déplacement pour congrès, par Immedica et Biomarin.

TANGO2 disease is a severe inherited disorder associating multiple symptoms such as metabolic crises, encephalopathy, cardiac arrhythmias, and hypothyroidism. The mechanism of action of TANGO2 is currently unknown. Here, we describe a cohort of 20 French patients bearing mutations in the TANGO2 gene. We found that the main clinical presentation was the association of neurodevelopmental delay (n = 17), acute metabolic crises (n = 17) and hypothyroidism (n = 12), with a large intrafamilial clinical variability. Metabolic crises included rhabdomyolysis (15/17), neurological symptoms (14/17), and cardiac features (12/17; long QT (n = 10), Brugada pattern (n = 2), cardiac arrhythmia (n = 6)) that required intensive care. We show previously uncharacterized triggers of metabolic crises in TANGO2 patients, such as some anesthetics and possibly l-carnitine. Unexpectedly, plasma acylcarnitines, plasma FGF-21, muscle histology, and mitochondrial spectrometry were mostly normal. Moreover, in patients' primary myoblasts, palmitate and glutamine oxidation rates, and the mitochondrial network were also normal. Finally, we found variable mitochondrial respiration and defective clearance of oxidized DNA upon cycles of starvation and refeeding. We conclude that TANGO2 disease is a life-threatening disease that needs specific cardiac management and anesthesia protocol. Mechanistically, TANGO2 disease is unlikely to originate from a primary mitochondrial defect. Rather, we suggest that mitochondrial defects are secondary to strong extrinsic triggers in TANGO2 deficient patients., (© 2020 SSIEM.)

Purpose: We aimed to identify prognostic factors for survival and long-term intellectual and developmental outcome in neonatal patients with early-onset urea cycle disorders (UCD) experiencing hyperammonaemic coma., Methods: We retrospectively analysed ammonia (NH3) and glutamine levels, electroencephalogram and brain images obtained during neonatal coma of UCD patients born between 1995 and 2011 and managed at a single centre and correlated them to survival and intellectual and developmental outcome., Results: We included 38 neonates suffering from deficiencies of argininosuccinate synthetase (ASSD, N = 12), ornithine transcarbamylase (OTCD, N = 10), carbamoylphosphate synthetase 1 (CPSD, N = 7), argininosuccinate lyase (ASLD, N = 7), N-acetylglutamate synthase (NAGS, N = 1) or arginase (ARGD, N = 1). Symptoms occurred earlier in mitochondrial than in cytosolic UCD. Sixty-eight percent of patients survived, with a mean (standard deviation-SD) follow-up of 10.4 (5.3) years. Mortality was mostly observed in OTCD (N = 7/10) and CPSD (N = 4/7) patients. Plasma NH3 level during the neonatal period, expressed as area under the curve, but not glutamine level was associated with mortality (p = .044 and p = .610). 62.1% of the patients had normal intellectual and developmental outcome. Intellectual and developmental outcome tended to correlate with UCD subtype (p = .052). No difference in plasma NH3 or glutamine level during the neonatal period among developmental outcomes was identified. EEG severity was linked to UCD subtypes (p = .004), ammonia levels (p = .037), duration of coma (p = .043), and mortality during the neonatal period (p = .020). Status epilepticus was recorded in 6 patients, 3 of whom died neonatally, 1 developed a severe intellectual disability while the 2 last patients had a normal development., Conclusion: UCD subtypes differed by survival rate, intellectual and developmental outcome and EEG features in the neonatal period. Hyperammonaemia expressed as area under the curve was associated with survival but not with intellectual and developmental outcome whereas glutamine was not associated with one of these outcomes. Prognostic value of video-EEG monitoring and the association between status epilepticus and mortality should be assessed in neonatal hyperammonaemic coma in further studies., Competing Interests: Declaration of Competing Interest Clément Pontoizeau, Célina Roda, Jean-Baptiste Arnoux, Patricia Vignolo-Diard, Anais Brassier, Florence Habarou, Valérie Barbier, Coraline Grisel, Marie-Thérèse Abi-Warde, Nathalie Boddaert, Alice Kuster, Aude Servais, Anna Kaminska, Carole Hennequin, Laurent Dupic, Fabrice Lesage, Guy Touati, Vassili Valayannopoulos, Bernadette Chadefaux-Vekemans, Mehdi Oualha, Monika Eisermann, Chris Ottolenghi and Pascale de Lonlay declare that they have no conflict of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To describe the health status of young patients affected by inborn errors of metabolism that require adherence to a restricted diet (IEMRDs) and to describe and compare their self- and proxy (parent)-reported quality of life (QoL) with reference values., Study Design: A cross-sectional study was conducted in 2015-2017 in patients affected by IEMRDs (except phenylketonuria) younger than 18 years. Data collection was based on medical records, clinical examinations, parents' and children's interviews, and self-reported questionnaires. Measurements included clinical and healthcare data, child and family environment data, and self- and proxy (parent)-reported QoL., Results: Of the 633 eligible participants, 578 were recruited (50.3% boys; mean age: 8.7 years); their anthropometric status did not differ from the general population. Approximately one-half of them had at least 1 complication of the disease. Their self-reported global QoL did not differ from that of the general population. However, relations with friends and leisure activities QoL domains were negatively impacted, whereas relations with medical staff, relations with parents, and self-esteem QoL domains were positively impacted. Their proxy (parent)-reported QoL was negatively impacted., Conclusions: Young patients affected by IEMRDs present a high rate of clinical complications. Although their proxy (parent)-reported QoL was negatively impacted, their self-reported QoL was variably impacted (both positively and negatively). These results may inform counseling for those who care for affected patients and their families., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Organ transplantation is discussed in methylmalonic aciduria (MMA) for renal failure, and poor quality of life and neurological outcome. We retrospectively evaluated 23 French MMA patients after kidney (KT), liver-kidney (LKT), and liver transplantation (LT). Two patients died, one after LKT, one of hepatoblastoma after KT. One graft was lost early after KT. Of 18 evaluable patients, 12 previously on dialysis, 8 underwent KT (mean 12.5 years), 8 LKT (mean 7 years), and 2 LT (7 and 2.5 years). At a median follow-up of 7.3 (KT), 2.3 (LKT), and 1.0 years (LT), no metabolic decompensation occurred except in 1 KT. Plasma and urine MMA levels dramatically decreased, more after LKT. Protein intake was increased more significantly after LKT than KT. Enteral nutrition was stopped in 7/8 LKT, 1/8 KT. Early complications were frequent after LKT. Neurological disorders occurred in four LKT, reversible in one. Five years after KT, four patients had renal failure. The metabolic outcomes were much better after LKT than KT. LKT in MMA is difficult but improves the quality of life. KT will be rarely indicated. We need more long-term data to indicate early LT, in the hope to delay renal failure and prevent neurodevelopmental complications., (© 2019 SSIEM.)

Background: HPRT deficiency is a rare disorder of purine metabolism whose natural history is not fully understood. No optimal management recommendations exist. The objective of the present study is to characterize a large cohort of patients with HPRT deficiency, comparing Lesch-Nyhan Disease (LND) and its attenuated variants, with the purpose of helping clinicians in disease management and prognostic definition., Methods: Genetic and clinical features of French and Italian patients with a confirmed diagnosis of HPRT deficiency were collected., Results: A hundred and one patients were studied, including 66 LND, 22 HND (HPRT-related Neurological Dysfunction) and 13 HRH (HPRT-Related Hyperuricemia) patients. The clinical manifestations at onset were not specific, but associated with an orange coloration of diapers in 22% of patients. The overall neurological involvement was more severe in LND than in HND patients. Behavioural disturbances were not limited to self-injuries and were not exclusive of LND. Median age of involuntary movements and self-injuries appearance in LND was 1.0 and 3 years, respectively. Renal manifestations (66.3% of patients) occurred at any age with a median onset age of 1.1 years, while gout (25.7% of patients) appeared later in disease course (median onset age 18 years) and was more frequent in attenuated variants than in LND. HPRT activity and genotype showed a significant correlation with the severity of the neurological disease. On the contrary, there were no significant differences in the development of nephropathy or gout. For the treatment of neurological aspects, botulinum toxin injections, oral or intrathecal baclofen and gabapentin were partially efficacious and well tolerated, while deep brain stimulation was associated to a worsening of patients' condition., Conclusions: The present study improves the knowledge of the natural history of HPRT deficiency and could represent a starting point for the development of future management guidelines., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Congenital disorders of glycosylation (CDG) includes ALG8 deficiency, a protein N-glycosylation defect with a broad clinical spectrum. If most of the 15 previously reported patients present an early-onset multisystem severe disease and early death, three patients including the cas princeps, present long-term survival and less severe symptoms., Methods: In order to further characterize ALG8-CDG, two new ALG8 patients are described and mRNA analyses of the ALG8-CDG cas princeps were effected., Results: One new patient exhibited a hepato-intestinal and neurological phenotype with two novel variants (c.91A > C p.Thr31Pro; c.139dup p.Thr47Asnfs*12). The other new patient, homozygous for a known variant (c.845C > T p.Ala282Val), presented a neurological phenotype with epilepsy, intellectual disability and retinis pigmentosa. The cas princeps ALG8-CDG patient was reported to have two heterozygous frameshift variants predicted to be without activity. We now described a novel ALG8 transcript variant in this patient and the 3D model of the putative encoded protein reveals no major difference with that of the normal ALG8 protein., Conclusion: The description of the two new ALG8 patients affirms that ALG8-CDG is a severe disease. In the cas princeps, as the originally described frameshift variants are degraded, the novel variant is promoted and could explain a milder phenotype.

Fructose-1,6-bisphosphatase (FBPase) deficiency is a very rare autosomal recessive disorder caused by a mutation of the fructose-1,6-bisphosphatase gene(FBP1). Disease is mainly revealed by hypoglycemia and lactic acidosis, both symptoms being characteristic for an enzymatic block in the last steps of the gluconeogenesis. Twelve patients with FBPase deficiency were diagnosed in France in the 2001-2013 period, using a diagnostic system based on a single blood sample which allows simultaneous enzyme activity measurement on mononuclear white blood cells and molecular analysis. Sequencing of exons and intron-exon junctions of FBP1 gene was completed in unsolved cases by a gene dosage assay developed for each exon. For most patients, first metabolic decompensation occurred before two years of age with a similar sequence: the triggering factors were fever, fasting, or decrease of food intake. However, diagnosis was made late at a mean age of 3 years, as mitochondrial defects or glycogen storage diseases were firstly suspected. Enzyme activity in leukocytes was dramatically decreased (<10%). Twelve different mutations were identified in 22 alleles among them seven were novels: one missense mutation c.472C > T, one point deletion c.48del, one point duplication c.865dupA, one deletion-insertion, and two splice mutations (c.427-1del and c.825 + 1G > A). We described the first intragenic deletion in FBP1 (g.97,364,754&#95;97,382,011del) in homozygous state. Our report also confirms that this very rare disease is misdiagnosed, as other energetic defects are firstly suspected.

PMM2-CDG (formerly known as CDG Ia) a deficiency in phosphomannomutase, is the most frequent congenital disorder of glycosylation. The phenotype encompasses a wide range of neurological and non-neurological manifestations comprising cerebellar atrophy and intellectual deficiency. The phenotype of the disorder is well characterized in children but the long term course of the disease is unknown and the phenotype of late onset forms has not been comprehensively described. We thus retrospectively collected the clinical, biological and radiological data of 29 French PMM2-CDG patients aged 15 years or more with a proven molecular diagnosis (16 females and 13 males). In addition, thirteen of these patients were reexamined at the time of the study to obtain detailed information. 27 of the 29 patients had a typical PMM2-CDG phenotype, with infantile hypotonia, strabismus, developmental delay followed by intellectual deficiency, epilepsy, retinitis pigmentosa and/or visceral manifestations. The main health problems for these patients as teenagers and in adulthood were primary ovarian insufficiency, growth retardation, coagulation anomalies and thrombotic events, skeletal deformities and osteopenia/osteoporosis, retinitis pigmentosa, as well as peripheral neuropathy. Three patients had never walked and three lost their ability to walk. The two remaining patients had a late-onset phenotype unreported to date. All patients (n = 29) had stable cerebellar atrophy. Our findings are in line with those of previous adult PMM2-CDG cohorts and points to the need for a multidisciplinary approach to the follow up of PMM2-CDG patients to prevent late complications. Additionally, our findings add weight to the view that PMM2-CDG may be diagnosed in teenage/adult patients with cerebellar atrophy, even in the absence of intellectual deficiency or non-neurological involvement.

Background: This study describes the natural history of Barth syndrome (BTHS)., Methods: The medical records of all patients with BTHS living in France were identified in multiple sources and reviewed., Results: We identified 16 BTHS pedigrees that included 22 patients. TAZ mutations were observed in 15 pedigrees. The estimated incidence of BTHS was 1.5 cases per million births (95%CI: 0.2-2.3). The median age at presentation was 3.1 weeks (range, 0-1.4 years), and the median age at last follow-up was 4.75 years (range, 3-15 years). Eleven patients died at a median age of 5.1 months; 9 deaths were related to cardiomyopathy and 2 to sepsis. The 5-year survival rate was 51%, and no deaths were observed in patients ≥3 years. Fourteen patients presented with cardiomyopathy, and cardiomyopathy was documented in 20 during follow-up. Left ventricular systolic function was very poor during the first year of life and tended to normalize over time. Nineteen patients had neutropenia. Metabolic investigations revealed inconstant moderate 3-methylglutaconic aciduria and plasma arginine levels that were reduced or in the low-normal range. Survival correlated with two prognostic factors: severe neutropenia at diagnosis (<0.5 × 109/L) and birth year. Specifically, the survival rate was 70% for patients born after 2000 and 20% for those born before 2000., Conclusions: This survey found that BTHS outcome was affected by cardiac events and by a risk of infection that was related to neutropenia. Modern management of heart failure and prevention of infection in infancy may improve the survival of patients with BTHS without the need for heart transplantation.

MCAD deficiency is the most common fatty acid oxidation disorder, with the prevalence varying from 1/10,000 to 1/27,000 in the countries adjacent to France. As the High Authority for Health has recently proposed including MCAD deficiency in the panel of diseases neonatally screened for in France, a consensus was written for the management of MCAD deficiency diagnosed either clinically or by neonatal screening. Patients may present acutely with hyperammonemia, hypoglycemia, encephalopathy, and hepatomegaly, mainly after a prolonged fast of intercurrent infection. Sudden death related to heartbeat disorders may also occur. The diagnosis of MCAD deficiency is suspected on the plasma acylcarnitine and/or the urinary organic acid profile. The diagnosis is confirmed by molecular biology and the enzymatic activity for patients who are not homozygous for the main mutation c.985A>G. However, some MCAD-deficient individuals may remain asymptomatic throughout life. The mainstay of treatment consists in avoiding prolonged fast and prescribing l-carnitine for patients who exhibit a deficiency in plasma carnitine. This management has radically modified the natural history of MCAD deficiency. This consensus will allow homogeneous management of these patients once the neonatal screening of MCAD deficiency has been introduced in France., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

Background: Deficiency of mitochondrial trifunctional protein (MTP) is caused by mutations in the HADHA and HADHB genes, which have been mostly delineated at the genomic DNA level and have not been always elucidated., Aim: To identify mutations in a French cohort of 52 MTP deficient patients and the susceptibility of mutations generating premature termination codons (PTCs) to the nonsense mRNA mediated decay (NMD)., Methods: Mutation screening in fibroblasts was performed at the cDNA level and real-time RT-PCR was used to compare the levels of the different PTC-bearing mRNAs before and after a treatment of fibroblasts by emetine, a translation inhibitor., Results: A mutation detection rate of 100% was achieved. A total of 22 novel mutations were identified, including a large-sized genomic deletion in HADHB gene. A high proportion of all identified mutations were non-sense, frameshift and splicing mutations, generating (PTCs), distributed essentially on HADHA coding regions. We could demonstrate that the majority of mutations resulting in PTCs conform to the established rules governing the susceptibility to NMD., Conclusion: Our results emphasize the value of cDNA analysis in the characterization of HADHA and HADHB mutations and further strengthen the model of haploinsufficiency as a major pathomechanism in MTP defects., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Objective: To better delineate the natural history of patients with methylmalonic aciduria (MMA)., Study Design: Thirty patients with vitamin-B12-unresponsive MMA (25 aged 1.5 to 22.0 years (y) at the end of the study and 5 who died during a metabolic crisis) were managed following standardized guidelines and studied retrospectively. The median follow-up was 8.3 y (range: 1.4-19.5). Patients were investigated with neuropsychological testing, brain MRIs, inulin clearances, biochemical and genetic studies., Results: Fifteen patients had a neonatal onset. Thirteen patients (43%) had significant neurological impairment. Chronic renal disease (CRD) occurred in 14 patients (47%) with a median age of onset of 6.5 y (range 1.5-18.6). Renal function further deteriorated in 4 patients within a median period of 5.8 y (range 2-7.4). Of 25 patients investigated at the enzymatic level, 17 were classified mut(o), 3 mut- and 5 cblA. Mortality, number of acute decompensations (p=0.031), median MMA urinary excretion (p=0.006) and neurological impairment (p<0.0001) were higher in mut degrees patients compared to mut-/cblA patients. Concerning the CRD, no difference incidence was found although the onset of CRD occurred earlier in mut(o) patients and was more severe., Conclusions: Our study provides unique data concerning the progression of renal disease in MMA. Patients with mut(o) phenotype have a more severe phenotype and probably an earlier and more severe CRD than patients with mut-/cblA phenotype.

We screened 11 unrelated French patients with congenital disorders of glycosylation (CDG) Ia for PMM2 mutations. Twenty one missense mutations on the 22 chromosomes (95%) including four novel mutations were identified: C9Y (G26A) in exon 1, L32R (TA95GC) in exon 2, and T226S (C677G) and C241S (G722C) in exon 8. We studied the PMM activity of these four novel mutant proteins and of the R141H mutant protein in an E coli expression system. The T226S, C9Y, L32R, and C241S mutant proteins have decreased specific activity (23 to 41% of normal), are all more or less thermolabile, and R141H has no detectable activity. Our results indicate that the new mutations identified here are less severe than the inactive R141H mutant protein, conferring residual PMM activity compatible with life.

Aim: To estimate the efficiency of metabolic screening in children's cardiomyopathy., Methods and Results: Blood glucose, lactate, pyruvate and ketone body, and carnitine levels were measured in 58 children referred with a cardiomyopathy of unknown origin. Organic acids, amino acids, oxidation of [1-14C] fatty acids to CO2 and dehydrogenation of [9,10(-3)H] fatty acids by lymphocytes were measured. Mitochondrial respiratory chain complex activity was measured in skeletal muscle and in endomyocardial biopsies. Acid a-glucosidase activity was measured in infants with hypertrophic cardio-myopathy. The prevalence of metabolic disorders was 22.4% (13/58-CL95%; 11.4-33.3%): four infants had a storage disease (Pompe's disease (3), Hurler's disease (1); two patients had a fatty acid beta-oxidation defect (systemic carnitine deficiency (1) and very-long chain acyl-CoA dehydrogenase deficiency (1)); respiratory enzyme deficiency was diagnosed in seven patients. This defect was confined to the myocardium in six. In the remaining 45 patients, metabolic screening was unrevealing., Conclusion: Metabolic screening should be performed in all children with cardiomyopathy as the prevalence of metabolic disorders is high in this population. This may help to define therapeutic strategy and to improve genetic counselling.