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Methylmalonic acidemia (MMA) is an inborn error of metabolism whose optimal management, especially in the long-term remains to be established.We describe the case of a child with MMA mutUsing the lowest effective therapeutic dose of CA and adjusting the patient's diet with caloric and protein intake adequate for her age and pathology, we managed to keep ammonium levels within the normal range, and to ensure a normal growth pattern.The present case adds further confirmation of the long-term management of MMA using CA, focusing on the long duration of follow up and on the use of a lower dose of CA in real life settings.

Morquio B disease is an attenuated phenotype within the spectrum of beta galactosidase (GLB1) deficiencies. It is characterised by dysostosis multiplex, ligament laxity, mildly coarse facies and heart valve defects due to keratan sulphate accumulation, predominantly in the cartilage. Morquio B patients have normal neurological development, setting them apart from those with the more severe GM1 gangliosidosis. Morquio B disease, with an incidence of 1:250.000 to 1:1.000.000 live births, is very rare. Here we report the clinical-biochemical data of nine patients. High amounts of keratan sulfate were detected using LC-MS/MS in the patients' urinary samples, while electrophoresis, the standard procedure of qualitative glycosaminoglycans analysis, failed to identify this metabolite in any of the patients' samples. We performed molecular analyses at gene, gene expression and protein expression levels, for both isoforms of the GLB1 gene, lysosomal GLB1, and the cell-surface expressed Elastin Binding Protein. We characterised three novel GLB1 mutations [c.75 + 2 T > G, c.575A > G (p.Tyr192Cys) and c.2030 T > G (p.Val677Gly)] identified in three heterozygous patients. We also set up a copy number variation assay by quantitative PCR to evaluate the presence of deletions/ insertions in the GLB1 gene. We propose a diagnostic plan, setting out the specific clinical- biochemical and molecular features of Morquio B, in order to avoid misdiagnoses and improve patients' management.

Lysosomal storage diseases (LSDs) are rare to extremely rare monogenic disorders. Their incidence, however, has probably been underestimated owing to their complex clinical manifestations. Sialidosis is a prototypical LSD inherited as an autosomal recessive trait and caused by mutations in the NEU1 gene that result in a deficiency of alpha-N-acetyl neuraminidase 1 (NEU1). Two basic forms of this disease, type I and type II, are known. The dysmorphic type II form features LSD symptoms including congenital hydrops, dysmorphogenetic traits, hepato-splenomegaly and severe intellectual disability. The diagnosis is more challenging in the normosomatic type I forms, whose clinical findings at onset include ocular defects, ataxia and generalized myoclonus. Here we report the clinical, biochemical and molecular analysis of five patients with sialidosis type I. Two patients presented novel NEU1 mutations. One of these patients was compound heterozygous for two novel NEU1 missense mutations: c.530A>T (p.Asp177Val) and c.1010A>G (p.His337Arg), whereas a second patient was compound heterozygous for a known mutation and a novel c.839G>A (p.Arg280Gln) mutation. We discuss the impact of these new mutations on the structural properties of NEU1. We also review available clinical reports of patients with sialidosis type I, with the aim of identifying the most frequent initial clinical manifestations and achieving more focused diagnoses.

Monoallelic variants in the KIF1A gene are associated with a large set of clinical phenotypes including neurodevelopmental and neurodegenerative disorders, underpinned by a broad spectrum of central and peripheral nervous system involvement. In a multicenter study conducted in patients presenting spastic gait or complex neurodevelopmental disorders, we analyzed the clinical, genetic and neuroradiological features of 28 index cases harboring heterozygous variants in KIF1A. We conducted a literature systematic review with the aim to comparing our findings with previously reported KIF1A-related phenotypes. Among 28 patients, we identified nine novel monoallelic variants, and one a copy number variation encompassing KIF1A. Mutations arose de novo in most patients and were prevalently located in the motor domain. Most patients presented features of a continuum ataxia-spasticity spectrum with only five cases showing a prevalently pure spastic phenotype and six presenting congenital ataxias. Seventeen mutations occurred in the motor domain of the Kinesin-1A protein, but location of mutation did not correlate with neurological and imaging presentations. When tested in 15 patients, muscle biopsy showed oxidative metabolism alterations (6 cases), impaired respiratory chain complexes II + III activity (3/6) and low CoQ10 levels (6/9). Ubiquinol supplementation (1gr/die) was used in 6 patients with subjective benefit. This study broadened our clinical, genetic, and neuroimaging knowledge of KIF1A-related disorders. Although highly heterogeneous, it seems that manifestations of ataxia-spasticity spectrum disorders seem to occur in most patients. Some patients also present secondary impairment of oxidative metabolism; in this subset, ubiquinol supplementation therapy might be appropriate.

Background Leigh syndrome (LS) is a progressive neurodegenerative disorder associated with primary or secondary dysfunction of mitochondrial oxidative phosphorylation and is the most common mitochondrial disease in childhood. Numerous reports on the biochemical and molecular profiles of LS have been published, but there are limited studies on genetically confirmed large series. We reviewed the clinical, imaging, biochemical and molecular data of 122 patients with a diagnosis of LS collected in the Italian Collaborative Network of Mitochondrial Diseases database. Results Clinical picture was characterized by early onset of several neurological signs dominated by central nervous system involvement associated with both supra- and sub-tentorial grey matter at MRI in the majority of cases. Extraneurological organ involvement is less frequent in LS than expected for a mitochondrial disorder. Complex I and IV deficiencies were the most common biochemical diagnoses, mostly associated with mutations in SURF1 or mitochondrial-DNA genes encoding complex I subunits. Our data showed SURF1 as the genotype with the most unfavorable prognosis, differently from other cohorts reported to date. Conclusion We report on a large genetically defined LS cohort, adding new data on phenotype-genotype correlation, prognostic factors and possible suggestions to diagnostic workup.

BackgroundLack of functional evidence hampers variant interpretation, leaving a large proportion of cases with a suspected Mendelian disorder without genetic diagnosis after genome or whole exome sequencing (WES). Research studies advocate to further sequence transcriptomes to directly and systematically probe gene expression defects. However, collection of additional biopsies, and establishment of lab workflows, analytical pipelines, and defined concepts in clinical interpretation of aberrant gene expression are still needed for adopting RNA-sequencing (RNA-seq) in routine diagnostics.MethodsWe implemented an automated RNA-seq protocol and a computational workflow with which we analyzed skin fibroblasts of 303 individuals with a suspected mitochondrial disease which previously underwent WES.ResultsWe detected on average 12,500 genes per sample including around 60% disease genes - a coverage substantially higher than with whole blood, supporting the use of skin biopsies. We prioritized genes demonstrating aberrant expression, aberrant splicing, or mono-allelic expression. The pipeline required less than one week from sample preparation to result reporting and provided a median of eight disease-associated genes per patient for inspection. A genetic diagnosis was established for 16% of the 205 WES-inconclusive cases. Detection of aberrant expression was a major contributor to diagnosis including instances of 50% reduction, which, together with mono-allelic expression, allowed for the diagnosis of dominant disorders caused by haploinsufficiency. Moreover, calling aberrant splicing and variants from RNA-seq data enabled detecting and validating splice-disrupting variants, of which the majority fell outside WES-covered regions.ConclusionTogether, these results show that streamlined experimental and computational processes can accelerate the implementation of RNA-seq in routine diagnostics.One sentence summaryImplementation of RNA-seq as a complementary tool in standard diagnostics achieves a 16% in diagnosis rate over whole exome sequencing.

Mucopolysaccharidosis are genetic disorders due to deficiency of lysosomal enzymes, resulting in abnormal glycosaminoglycans accumulation in several tissues. Heart involvement tends to be progressive and worsens with age. We describe the first case of mucopolysaccharidosis type I presenting with noncompaction/dilated-mixed cardiomyopathy and heart failure within neonatal period, which responded successfully to specific metabolic treatment. Cardiac function recovered after enzyme replacement therapy and hematopoietic stem cell transplantation, adding to the existing knowledge of the disease., Highlights • MPS can present with acute cardiac failure and cardiomyopathy within neonatal period. • Cardiomyopathies associated with MPS include also noncompaction phenotypes. • Heart failure due to MPS can respond successfully to specific metabolic treatment. • Consider complete metabolic tests in case of inexplicable neonatal heart failure.

Background Mutations in lysyl-tRNA synthetase (KARS1), an enzyme that charges tRNA with the amino acid lysine in both the cytoplasm and mitochondria, have been associated thus far with autosomal recessive Charcot–Marie–Tooth type CMTRIB, hearing loss type DFNB89, and mitochondrial encephalohepatopathy (MEH) featuring neurodevelopmental disorders with microcephaly, white matter changes, and cardiac and hepatic failure in less than 30 patients. Case presentation We report the clinical, biochemical and molecular findings of a 14-month-old girl with severe MEH compatible clinical features, profound sensorineural hearing loss, leopard spot retinopathy, pancytopenia, and advanced liver disease with portal hypertension leading to death at the age of 30 months. Conclusions Whole exome sequencing identified two rare variants in KARS1 gene. Our report expands the allelic and clinical features of tRNA synthase disorders. Moreover, with our report we confirm the usefulness of WES as first tier diagnostic method in infants with complex multisystem phenotypes.

Patients with mitochondrial diseases, who usually manifest a multisystem disease, are considered potentially at-risk for a severe coronavirus disease 2019 (COVID-19). The objective of this study is to analyze the clinical features, prognosis and outcomes of COVID-19 in patients with primary mitochondrial diseases in a cohort of patients followed in Italy. We searched for patients with primary mitochondrial diseases and COVID-19 followed by the Italian Collaborative Network of Mitochondrial Diseases. In a total of 1843 patients followed by the National Network, we have identified from March 1st to January 30th, 2021, 27 SARS-CoV-2 infection. Most of the patients were pauci or asymptomatic (85%) and treated at home. The most common signs of COVID-19 were fever (78,9%), fatigue (47,4%), myalgia (42,1%), cough and headache (36,8%), and dyspnea (31,6%). Those who required COVID-19 therapy were treated with low-molecular-weight heparin, glucocorticoids, and antibiotics (mainly azithromycin) without serious side effects related to the therapy. Five patients (18,5%) clinically deteriorated during the infection, and one of them died for pneumonia. Primary mitochondrial diseases infected individuals seemed to be similarly affected by SARS-CoV-2 compared with the general Italian population in terms of clinical presentation and outcome.

Mitochondrial diseases (MDs) are a large group of genetically determined multisystem disorders, characterized by extreme phenotypic heterogeneity, attributable in part to the dual genomic control (nuclear and mitochondrial DNA) of the mitochondrial proteome. Advances in next-generation sequencing technologies over the past two decades have presented clinicians with a challenge: to select the candidate disease-causing variants among the huge number of data provided. Unfortunately, the clinical tools available to support genetic interpretations still lack specificity and sensitivity. For this reason, the diagnosis of MDs continues to be difficult, with the new “genotype first” approach still failing to diagnose a large group of patients. With the aim of investigating possible relationships between clinical and/or biochemical phenotypes and definitive molecular diagnoses, we performed a retrospective multicenter study of 111 pediatric patients with clinical suspicion of MD. In this cohort, the strongest predictor of a molecular (in particular an mtDNA-related) diagnosis of MD was neuroimaging evidence of basal ganglia (BG) involvement. Regression analysis confirmed that normal BG imaging predicted negative genetic studies for MD. Psychomotor regression was confirmed as an independent predictor of a definitive diagnosis of MD. The findings of this study corroborate previous data supporting a role for neuroimaging in the diagnostic approach to MDs and reinforce the idea that mtDNA sequencing should be considered for first-line testing, at least in specific groups of children.

Movement disorders are increasingly being recognized as a manifestation of childhood-onset mitochondrial diseases (MDs). However, the spectrum and characteristics of these conditions have not been studied in detail in the context of a well-defined cohort of patients. We retrospectively explored a cohort of individuals with childhood-onset MDs querying the Nationwide Italian Collaborative Network of Mitochondrial Diseases database. Using a customized online questionnaire, we attempted to collect data from the subgroup of patients with movement disorders. Complete information was available for 102 patients. Movement disorder was the presenting feature of MD in 45 individuals, with a mean age at onset of 11 years. Ataxia was the most common movement disorder at onset, followed by dystonia, tremor, hypokinetic disorders, chorea, and myoclonus. During the disease course, most patients (67.7%) encountered a worsening of their movement disorder. Basal ganglia involvement, cerebral white matter changes, and cerebellar atrophy were the most commonly associated neuroradiological patterns. Forty-one patients harbored point mutations in the mitochondrial DNA, 10 carried mitochondrial DNA rearrangements, and 41 cases presented mutations in nuclear-DNA-encoded genes, the latter being associated with an earlier onset and a higher impairment in activities of daily living. Among our patients, 32 individuals received pharmacological treatment; clonazepam and oral baclofen were the most commonly used drugs, whereas levodopa and intrathecal baclofen administration were the most effective. A better delineation of the movement disorders phenotypes starting in childhood may improve our diagnostic workup in MDs, fine tuning management, and treatment of affected patients.

The heterogeneous group of mitochondrial disorders (MDs) is by far the largest class of inborn errors of metabolism, having a collective incidence of 1.6 in 5000.1 Over the past decade, routine clinical use of next-generation sequencing (NGS) has allowed a considerable number of cases to receive a precise molecular diagnosis. At present, however, NGS approaches, including targeted multigene panels and exome sequencing, still fail to achieve molecular definition in about half of patients with MD with a confirmed biochemical and clinical diagnosis.2 These unresolved cases could be due to new (‘hyper-rare’) genes/loci; alternatively, they could be linked to limits of current NGS strategies: indeed, mosaicisms requiring high sequencing depth for detection, genomic rearrangements including small and large deletions/insertions ( 50 bp, respectively), and structural changes such as chromosomal rearrangements (inversions, translocations, deletions, duplications) all usually escape traditional NGS analysis pipelines. The chronic limited use of whole-genome sequencing in diagnostic settings may contribute to the substantial number of unresolved cases. The presence of repeat expansions and variants in deep intronic and regulatory regions2 may also provide an explanation for ‘missing heritability’. Although relatively rare, UPD might explain the unsolved transmission of homozygous mutations or aberrant patterns of imprinting,3 even in MDs. Here, we describe the cases of two children, each with a clinical diagnosis of MD, in whom chromosomal microarray analysis (CMA) allowed detection of UPD and helped to substantiate a homozygous variant identified by NGS. This study was conducted in accordance with Italian National Health System guidelines and the Declaration of Helsinki. Patient 1 is a child who, when first seen by us, presented with generalised tonic-clonic seizures, hypotonia and …

Background Primary mitochondrial disorders (PMD) are rare conditions resulting in progressive multi-organ failure. Cardiovascular involvement (CVI) has been reported in paediatric patients. However, its age-related prevalence, clinical presentation and prognostic impact are unresolved. We detailed CVI in a cohort of children diagnosed with PMD over two decades at a tertiary referral centre. Results We enrolled 86 PMD patients (M/F = 30/56; mean age 6.4 ± 8.58 years). CVI was detected in 31 patients (36%), with mean age at onset of 5.7 ± 7.8 years including the pre- and neonatal phase in 14, often representing the first sign of PMD (42% of those with CVI). Heart disease resulted more common in males and in children with specific aetiologies (Barth, TMEM70 and MELAS syndromes). Hypertrophic, non-compaction and dilated cardiomyopathies were the prevalent disorders, although pulmonary arterial hypertension was also found. Adverse cardiac events (heart failure, resuscitated cardiac arrest, ICD/PM implantation, sudden death) occurred in 19% of children with CVI over a follow-up period of 5.4 ± 4.3 years. All-cause mortality was higher in patients with CVI compared to those without CVI (45.1% vs 21.8%; p Conclusion Cardiovascular involvement occurred in over one-third of children diagnosed with PMD, often at a very early age, and was associated with adverse prognosis. Final outcome of PMD-related CVI was influenced by the specific underlying aetiology, suggesting the need for tailored management of heart failure and sudden death prevention.

We describe a 14-month-old boy, with a previous diagnosis of propionic acidemia (PA) by expanded newborn screening, who, admitted for a suspected metabolic crisis, tested positive for SARS-CoV-2. Since propionic acidemia was diagnosed, the patient has followed the recommended diet for this inborn error of metabolism. Although propionic acidemia patients are at a high risk of suffering metabolic crises, frequently associated with permanent clinical complications, psychomotor development of this patient was normal. The SARS-CoV-2 infection (at about 1 year of age) caused the patient’s first metabolic crisis. However, his clinical course was in keeping with a mild clinical form of COVID-19, and he recovered without experiencing severe clinical consequences. We describe this patient in order to improve the knowledge about follow up of PA patients identified by newborn screening and to increase the limited number of reports of SARS-CoV-2 infection in children with comorbidities, especially inborn errors of metabolism.

Spastic paraplegia 35 (SPG35) is a recessive condition characterized by childhood onset, progressive course, complicated by dystonia, dysarthria, cognitive impairment, and epilepsy. Mutations in the FA2H gene have been described in several families, leading to the proposal of a single entity, named fatty acid hydrolase-associated neurodegeneration (FAHN). Several reports have described a polymorphic radiological picture with white matter lesions of various degrees and a distinct form of neurodegeneration with brain iron accumulation. While we reviewed the pertinent literature, we also report three new patients with SPG35, highlighting the possible absence of white matter lesions even after a long neuroimaging follow-up. Three-dimensional modeling of the mutated proteins was helpful to elucidate the role of the site of mutations and the correlation with the residual enzyme activity as determined in cultured skin fibroblasts.

Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encepha- lomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial en- cephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was ex- cluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a hu- man disease and encodes an enzyme responsible for 2’-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2’-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead com- pletely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation.

Objective To describe clinical, biochemical, and molecular genetic findings in a large inbred family in which 4 children with a severe early-onset epileptic-dyskinetic encephalopathy, with suppression burst EEG, harbored homozygous mutations of phosphatidylinositol glycan anchor biosynthesis, class P (PIGP), a member of the large glycosylphosphatidylinositol (GPI) anchor biosynthesis gene family. Methods We studied clinical features, EEG, brain MRI scans, whole-exome sequencing (WES), and measured the expression of a subset of GPI-anchored proteins (GPI-APs) in circulating granulocytes using flow cytometry. Results The 4 affected children exhibited a severe neurodevelopmental disorder featuring severe hypotonia with early dyskinesia progressing to quadriplegia, associated with infantile spasms, focal, tonic, and tonic-clonic seizures and a burst suppression EEG pattern. Two of the children died prematurely between age 2 and 12 years; the remaining 2 children are aged 2 years 7 months and 7 years 4 months. The homozygous c.384del variant of PIGP, present in the 4 patients, introduces a frame shift 6 codons before the expected stop signal and is predicted to result in the synthesis of a protein longer than the wild type, with impaired functionality. We demonstrated a reduced expression of the GPI-AP CD16 in the granulocytic membrane in affected individuals. Conclusions PIGP mutations are consistently associated with an epileptic-dyskinetic encephalopathy with the features of early infantile epileptic encephalopathy with profound disability and premature death. CD16 is a valuable marker to support a genetic diagnosis of inherited GPI deficiencies.

GM1 ganglioside, a monosialic glycosphingolipid and a crucial component of plasma membranes, accumulates in lysosomal storage disorders, primarily in GM1 gangliosidosis. The development of biomarkers for simplifying diagnosis, monitoring disease progression and evaluating drug therapies is an important objective in research into neurodegenerative lysosomal disorders. With this in mind, we established fluorescent imaging and flow-cytometric methods to track changes in GM1 ganglioside levels in patients with GM1 gangliosidosis and in control cells. We also evaluated GM1 ganglioside content in patients’ cells treated with the commercially available Miglustat, a substrate inhibitor potentially suitable for the treatment of late-onset GM1 gangliosidosis. The flow-cytometric method proved to be sensitive, unbiased, and rapid in determining variations in GM1 ganglioside content in human lymphocytes derived from small amounts of fresh blood. We detected a strong correlation between GM1 ganglioside content and the clinical severity of GM1 gangliosidosis. We confirm the ability of Miglustat to act as a substrate reduction agent in the patients’ treated cells. As well as being suitable for diagnosing and managing patients with GM1 gangliosidosis this method could be useful in the diagnosis and management of other lysosomal diseases, such as galactosialidosis, Type C Niemann-Pick, and any other disease with pathologic variations of GM1 ganglioside.

Background Patients with Gaucher Disease (GD) exhibit three phenotypes, including type 1 (non-neuronopathic), type 2 (acute neuronopathic), and type 3 (subacute neuronopathic). Aim Identifying which GBA changes represent benign polymorphisms and which may result in disease-causing mutations is essential for diagnosis and genotype/phenotype correlations but is often challenging. Results Here, we describe a patient with type 3 GD, presenting with drug-resistant epilepsy, who bears a set of GBA polymorphic variants including the novel c.363A > G (Gly82Gly) synonymous mutation. In silico predictions, mRNA and functional studies revealed that the new Gly82Gly mutation causes skipping of GBA exon 4, leading to a severe reduction of the wild type GBA mRNA. This is the first report of a synonymous change causing GD through loss of an exonic splicing enhancer sequence. The synonymous mutation is in trans with the Asn188Ser missense mutation, thus making the Asn188Ser responsible for the patient’s phenotype and strengthening the association of Asn188Ser with the particular neurological phenotype of type 3 GD. Conclusion We strengthen the association of Asn188Ser with the type 3 GD phenotype and progressive myoclonus epilepsy. Our data confirm that in silico predictions and mRNA analysis are mandatory in discriminating pathological mutations from the background of harmless polymorphisms, especially synonymous changes.

ObjectiveTo describe clinical, biochemical, and molecular genetic findings in a large inbred family in which 4 children with a severe early-onset epileptic-dyskinetic encephalopathy, with suppression burst EEG, harbored homozygous mutations of phosphatidylinositol glycan anchor biosynthesis, class P (PIGP), a member of the large glycosylphosphatidylinositol (GPI) anchor biosynthesis gene family.MethodsWe studied clinical features, EEG, brain MRI scans, whole-exome sequencing (WES), and measured the expression of a subset of GPI-anchored proteins (GPI-APs) in circulating granulocytes using flow cytometry.ResultsThe 4 affected children exhibited a severe neurodevelopmental disorder featuring severe hypotonia with early dyskinesia progressing to quadriplegia, associated with infantile spasms, focal, tonic, and tonic-clonic seizures and a burst suppression EEG pattern. Two of the children died prematurely between age 2 and 12 years; the remaining 2 children are aged 2 years 7 months and 7 years 4 months. The homozygous c.384del variant of PIGP, present in the 4 patients, introduces a frame shift 6 codons before the expected stop signal and is predicted to result in the synthesis of a protein longer than the wild type, with impaired functionality. We demonstrated a reduced expression of the GPI-AP CD16 in the granulocytic membrane in affected individuals.ConclusionsPIGP mutations are consistently associated with an epileptic-dyskinetic encephalopathy with the features of early infantile epileptic encephalopathy with profound disability and premature death. CD16 is a valuable marker to support a genetic diagnosis of inherited GPI deficiencies.

We present a 29-year-old man with visual failure since childhood, muscle weakness, subtle heart muscle hypertrophy, and seizures who was initially considered to be affected by a mitochondrial encephalomyopathy because of the multiple unspecific involvement of brain, muscle and retinal tissues. Only the muscle biopsy findings correctly guided the genetic investigations and the identification of an autophagic vacuolar myopathy due to a homozygous mutation in CLN3. We believe that information in autophagic muscle disorders should further alert clinicians to consider CLN3 in individuals with vacuolar myopathy, especially if they have visual and cardiac involvement.

Objective: To describe electroclinical features and outcome of 6 patients harboring KCNB1 mutations. Methods: Clinical, EEG, neuropsychological, and brain MRI data analysis. Targeted next-generation sequencing of a 95 epilepsy gene panel. Results: The mean age at seizure onset was 11 months. The mean follow-up of 11.3 years documented that 4 patients following an infantile phase of frequent seizures became seizure free; the mean age at seizure offset was 4.25 years. Epilepsy phenotypes comprised West syndrome in 2 patients, infantile-onset unspecified generalized epilepsy, myoclonic and photosensitive eyelid myoclonia epilepsy resembling Jeavons syndrome, Lennox-Gastaut syndrome, and focal epilepsy with prolonged occipital or clonic seizures in each and every one. Five patients had developmental delay prior to seizure onset evolving into severe intellectual disability with absent speech and autistic traits in one and stereotypic hand movements with impulse control disorder in another. The patient with Jeavons syndrome evolved into moderate intellectual disability. Mutations were de novo, 4 missense and 2 nonsense, 5 were novel, and 1 resulted from somatic mosaicism. Conclusions: KCNB1-related manifestations include a spectrum of infantile-onset generalized or focal seizures whose combination leads to early infantile epileptic encephalopathy including West, Lennox-Gastaut, and Jeavons syndromes. Long-term follow-up highlights that following a stormy phase, seizures subside or cease and treatment may be eased or withdrawn. Cognitive and motor functions are almost always delayed prior to seizure onset and evolve into severe, persistent impairment. Thus, KCNB1 mutations are associated with diffuse brain dysfunction combining seizures, motor, and cognitive impairment.

Juvenile and adult GM1-gangliosidosis are invariably characterized by progressive neurological deterioration. To date only symptomatic therapies are available. We report for the first time the positive results of Miglustat (OGT 918, N-butyl-deoxynojirimycin) treatment on three Italian GM1-gangliosidosis patients. The first two patients had a juvenile form (enzyme activity ≤5%, GLB1 genotype p.R201H/c.1068 + 1G > T; p.R201H/p.I51N), while the third patient had an adult form (enzyme activity about 7%, p.T329A/p.R442Q). Treatment with Miglustat at the dose of 600 mg/day was started at the age of 10, 17 and 28 years; age at last evaluation was 21, 20 and 38 respectively. Response to treatment was evaluated using neurological examinations in all three patients every 4–6 months, the assessment of Movement Disorder-Childhood Rating Scale (MD-CRS) in the second patient, and the 6-Minute Walking Test (6-MWT) in the third patient. The baseline neurological status was severely impaired, with loss of autonomous ambulation and speech in the first two patients, and gait and language difficulties in the third patient. All three patients showed gradual improvement while being treated; both juvenile patients regained the ability to walk without assistance for few meters, and increased alertness and vocalization. The MD-CRS class score in the second patient decreased from 4 to 2. The third patient improved in movement and speech control, the distance covered during the 6-MWT increased from 338 to 475 m. These results suggest that Miglustat may help slow down or reverse the disease progression in juvenile/adult GM1-gangliosidosis.

Behr syndrome is characterized by the association of early onset optic atrophy, cerebellar ataxia, pyramidal signs, peripheral neuropathy and mental retardation. Recently, some cases were reported to be caused by biallelic mutations in OPA1 . We describe an 11-year-old girl (Pt1) and a 7-year-old boy (Pt2) with cognitive delay, ataxic gait and clinical signs suggestive of a peripheral neuropathy, with onset in early infancy. In Pt1 ocular fundus examination revealed optic disk pallor whereas Pt2 exhibited severe optic atrophy. In both children neuroimaging detected a progressive cerebellar involvement accompanied by basal ganglia hyperintensities and pathological peak levels of lactate. In both patients, muscle biopsy showed diffuse reduction of cytochrome c oxidase stain, some atrophic fibers and type II fiber grouping. Using a targeted resequencing panel in next generation sequencing, we identified the homozygous c.1180G>A/p.Ala394Thr mutation in Pt1 and the c.2779-2A>C mutation in compound heterozygosity with the c.2809C>T/p.Arg937Cys mutation in Pt2. All variants were novel and segregated in the healthy parents. Expression of OPA1 protein was significantly reduced in muscle tissues of both patients by Western blotting. We also observed in patients' fibroblasts a higher proportion of fragmented and intermediate mitochondria upon galactose treatment compared to controls, as already seen in other patients harboring mutations in OPA1 . The presence of Leigh-like neuroimaging features is a novel finding in Behr syndrome and further adds to the complex genotype–phenotype correlations in OPA1 -associated disorders.

Inborn defects of cholesterol biosynthesis are metabolic disorders presenting with multi-organ and tissue anomalies. An autosomal recessive defect involving the demethylating enzyme C4-methyl sterol (SC4MOL) has been reported in only 4 patients so far. In infancy, all patients were affected by microcephaly, bilateral congenital cataracts, growth delay, psoriasiform dermatitis, immune dysfunction, and intellectual disability. Herein, we describe a new case of SC4MOL deficiency in which a 19-year-old Italian male was affected by bilateral congenital cataracts, growth delay and learning disabilities, behavioral disorders and small stature, but not microcephaly. Our patient had abundant scalp dandruff, without other skin manifestations. Analysis of the blood sterol profile showed accumulation of C4-monomethyl and C4-dimethyl sterols suggesting a deficiency of the SC4MOL enzyme. Sequencing of the MSMO1 gene (also known as the “ SC4MOL ” gene) confirmed mutations in each allele (c.731A > G, p.Y244C, which is already known, and c.605G > A, p.G202E, which is a novel variant). His father carried c.731A > G mutation, whereas his mother carried c.605G > A. Thus, the combination of multiple skills and methodologies, in particular, blood sterol profiling and genetic analysis, led to the diagnosis of a new case of a very rare defect of cholesterol biosynthesis. Consequently, we suggest that these two analyses should be performed as soon as possible in all undiagnosed patients affected by bilateral cataracts and developmental delay.

BACKGROUND: The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys. SUBJECTS AND METHODS: A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS). RESULTS: The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p

Drop attacks are sudden, spontaneous falls without loss of consciousness, followed by rapid recovery. Causes in children include severe epilepsies, movement disorders, cataplexy, and psychiatric disorders. We describe two children (a 3-year-old female and a 12-year-old male) with mild neuromotor delay and sudden falls appearing upon starting to walk. Extensive clinical and laboratory investigation was unremarkable. Twenty to 22 months after the onset of falls, both children developed subtle choreiform movements, affecting all four limbs, leading to frequent falls, at times causing traumatic injury. A heterozygous mutation of the TITF1/NKX2-1 gene (14q13) was detected in both patients, allowing the diagnosis of benign hereditary chorea (BHC). Treatment with levodopa attenuated abnormal movements and led to disappearance of drop attacks. A diagnosis of BHC should be considered in young children with recurrent and unexplained drop attacks, especially if associated with neuromotor delay, even in the absence of choreiform movements.

Objective:To describe electroclinical features and outcome of 6 patients harboring KCNB1 mutations.Methods:Clinical, EEG, neuropsychological, and brain MRI data analysis. Targeted next-generation sequencing of a 95 epilepsy gene panel.Results:The mean age at seizure onset was 11 months. The mean follow-up of 11.3 years documented that 4 patients following an infantile phase of frequent seizures became seizure free; the mean age at seizure offset was 4.25 years. Epilepsy phenotypes comprised West syndrome in 2 patients, infantile-onset unspecified generalized epilepsy, myoclonic and photosensitive eyelid myoclonia epilepsy resembling Jeavons syndrome, Lennox-Gastaut syndrome, and focal epilepsy with prolonged occipital or clonic seizures in each and every one. Five patients had developmental delay prior to seizure onset evolving into severe intellectual disability with absent speech and autistic traits in one and stereotypic hand movements with impulse control disorder in another. The patient with Jeavons syndrome evolved into moderate intellectual disability. Mutations were de novo, 4 missense and 2 nonsense, 5 were novel, and 1 resulted from somatic mosaicism.Conclusions:KCNB1-related manifestations include a spectrum of infantile-onset generalized or focal seizures whose combination leads to early infantile epileptic encephalopathy including West, Lennox-Gastaut, and Jeavons syndromes. Long-term follow-up highlights that following a stormy phase, seizures subside or cease and treatment may be eased or withdrawn. Cognitive and motor functions are almost always delayed prior to seizure onset and evolve into severe, persistent impairment. Thus, KCNB1 mutations are associated with diffuse brain dysfunction combining seizures, motor, and cognitive impairment.