Search

Sulphated proteoglycans are essential in skeletal and brain development. Recently, pathogenic variants in genes encoding proteins involved in the proteoglycan biosynthesis have been identified in a range of chondrodysplasia associated with intellectual disability. Nevertheless, several patients remain with unidentified molecular basis. This study aimed to contribute to the deciphering of new molecular bases in patients with chondrodysplasia and neurodevelopmental disease. Exome sequencing was performed to identify pathogenic variants in patients presenting with chondrodysplasia and intellectual disability. The pathogenic effects of the potentially causative variants were analysed by functional studies. We identified homozygous variants (c.1218_1220del and c.1224_1225del) in SLC35B2 in two patients with pre- and postnatal growth retardation, scoliosis, severe motor and intellectual disabilities and hypomyelinating leukodystrophy. By functional analyses, we showed that the variants affect SLC35B2 mRNA expression and protein subcellular localization leading to a functional impairment of the protein. Consistent with those results, we detected proteoglycan sulphation impairment in SLC35B2 patient fibroblasts and serum. Our data support that SLC35B2 functional impairment causes a novel syndromic chondrodysplasia with hypomyelinating leukodystrophy, most likely through a proteoglycan sulphation defect. This is the first time that SLC35B2 variants are associated with bone and brain development in human.

IntroductionThis study aims to define the phenotypic and molecular spectrum of the two clinical forms of β-galactosidase (β-GAL) deficiency, GM1-gangliosidosis and mucopolysaccharidosis IVB (Morquio disease type B, MPSIVB).MethodsClinical and genetic data of 52 probands, 47 patients with GM1-gangliosidosis and 5 patients with MPSIVB were analysed.ResultsThe clinical presentations in patients with GM1-gangliosidosis are consistent with a phenotypic continuum ranging from a severe antenatal form with hydrops fetalis to an adult form with an extrapyramidal syndrome. Molecular studies evidenced 47 variants located throughout the sequence of the GLB1 gene, in all exons except 7, 11 and 12. Eighteen novel variants (15 substitutions and 3 deletions) were identified. Several variants were linked specifically to early-onset GM1-gangliosidosis, late-onset GM1-gangliosidosis or MPSIVB phenotypes. This integrative molecular and clinical stratification suggests a variant-driven patient assignment to a given clinical and severity group.ConclusionThis study reports one of the largest series of b-GAL deficiency with an integrative patient stratification combining molecular and clinical features. This work contributes to expand the community knowledge regarding the molecular and clinical landscapes of b-GAL deficiency for a better patient management.

Fingerprint bodies are observed in a variety of clinical situations with no definite genetic cause identified so far. We report for the first time the association of fingerprint bodies with rods in a patient who developed a slowly progressive myopathy affecting the face and limb extremities. Ultrastructural examination first disclosed fingerprint bodies and on a second biopsy, associated cytoplasmic bodies and rods. Next Generation Sequencing panel of congenital nemaline myopathy genes allowed the identification of two novel variants, a deleterious missense variant (c.1628G>T, p.Arg543Leu) located in the WASP-homology 2 domain, and a deletion (c.366delG, p.Lys122AsnFs*6) in the LMOD3 gene, generally causing severe nemaline myopathy with antenatal onset and early death. Recently, a less severe phenotype similar to our case has been reported. Our study confirms the existence of milder phenotypes linked to LMOD3 mutations and underlines that fingerprint bodies, though not specific, may be an early ultrastructural marker that could be linked, among others, to nemaline myopathy.

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disorder characterized by progressive motor and respiratory decline during the first year of life. Early and late-onset cases have recently been reported, although not meeting the established diagnostic criteria, these cases have been genotyped. We thus conducted a national multicenter observational retrospective study to determine the prognosis of children with SMARD1 according to their phenotype. We recorded all known French pediatric cases with mutations identified on the immunoglobulin μ-binding protein 2 gene and the presence of respiratory symptoms. Thirty centers provided 22 observations. A diaphragmatic palsy was diagnosed 1.5 months (p = 0.02) after first respiratory symptoms, and hypotonia preceded areflexia by 4 months (p = 0.02). Early onset of symptoms leading to specialist consultation before the age of 3 months was associated with a significantly worse prognosis (p

Background Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder characterized by degeneration of the anterior horn cells of the spinal cord. Nusinersen has been covered by public healthcare in France since May 2017. The aim of this article is to report results after 1 year of treatment with intrathecal nusinersen in children with SMA types 1 and 2 in France. Comparisons between treatment onset (T0) and after 1 year of treatment (Y1) were made in terms of motor function and need for nutritional and ventilatory support. Motor development milestone achievements were evaluated using the modified Hammersmith Infant Neurologic Examination–Part 2 (HINE-2) for patients under 2 years of age and Motor Function Measure (MFM) scores for patients over 2 years of age. Results Data on 204 SMA patients (type 1 or 2) were retrospectively collected from the 23 French centers for neuromuscular diseases. One hundred and twenty three patients had been treated for at least 1 year and were included, 34 of whom were classified as type 1 (10 as type 1a/b and 24 as type 1c) and 89 as type 2. Survival motor Neuron 2 (SMN2) copy numbers were available for all but 6 patients. Patients under 2 years of age (n = 30), had significantly higher HINE-2 scores at year 1 than at treatment onset but used more nutritional and ventilatory support. The 68 patients over 2 years of age evaluated with the Motor Function Measure test had significantly higher overall scores after 1 year, indicating that their motor function had improved. The scores were higher in the axial and proximal motor function (D2) and distal motor function (D3) parts of the MFM scale, but there was no significant difference for standing and transfer scores (D1). No child in either of the two groups achieved walking. Conclusion Nusinersen offers life-changing benefits for children with SMA, particularly those with more severe forms of the disorder. Caregiver assessments are positive. Nevertheless, patients remain severely disabled and still require intensive support care. This new treatment raises new ethical challenges.

International audience; BACKGROUND:The imaging features of Huntington disease are well known in adults, unlike in juvenile-onset Huntington disease.OBJECTIVE:To conduct a morphometric magnetic resonance imaging (MRI) analysis in three juvenile Huntington disease patients (ages 2, 4 and 6 years old) to determine whether quantitative cerebral and cerebellar morphological metrics may provide diagnostically interesting patterns of cerebellar and cerebellar atrophy.MATERIALS AND METHODS:We report the cases of three siblings with extremely early presentations of juvenile Huntington disease associated with dramatic expansions of the morbid paternal allele from 43 to more than 100 CAG trinucleotide repeats. Automatic segmentation of MRI images of the cerebrum and cerebellum was performed and volumes of cerebral substructures and cerebellar lobules of juvenile Huntington disease patients were compared to those of 30 normal gender- and age-matched controls. Juvenile Huntington disease segmented volumes were compared to those of age-matched controls by using a z-score.RESULTS:Three cerebral substructures (caudate nucleus, putamen and globus pallidus) demonstrated a reduction in size of more than three standard deviations from the normal mean although it was not salient in one of them at clinical reading and was not diagnosed. The size of cerebellum lobules, cerebellum grey matter and cerebellum cortex was reduced by more than two standard deviations in the three patients. The cerebellar atrophy was predominant in the posterior lobe.CONCLUSION:Our study sheds light on atrophic cerebral and cerebellar structures in juvenile Huntington disease. Automatic segmentations of the cerebellum provide patterns that may be of diagnostic interest in this disease.

We describe the case of a young patient with calcifying encephalopathy, born to asymptomatic parents. An extensive hypothesis-driven etiological assessment was performed and failed to detect the precise etiology during many years. We therefore decided to perform whole exome sequencing of the child-unaffected parents trio. A de novo pathogenic variant in the IFIH1 gene which has recently been shown to cause autosomal dominant forms of Aicardi-Goutieres syndrome was identified. This child presented with a severe form with neonatal thrombocytopenia and hepatomegaly, the latter having been detected during late gestation. Although first milestones were uneventful, he progressively lost motor skills from the age of 12 months and developed severe spastic paraplegia. Brain imaging revealed white matter abnormalities and extensive calcifications. He also presented atypical skin lesions, different from chilblains. His medical history was marked by two episodes of acute pancreatitis. We provide herein the results of pathological examination including detailed description of the neuropathological hallmarks. To our knowledge, this the first detailed clinico-pathological description of a patient with an IFIH1 pathogenic variant.

International audience; Introduction Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a rare genetic disorder due to mutations or deletions in SLC2A1, resulting in impaired glucose uptake through the blood brain barrier. The classic phenotype includes pharmacoresistant epilepsy, intellectual deficiency, microcephaly and complex movement disorders, with hypoglycorrhachia, but milder phenotypes have been described (carbohydrate-responsive phenotype, dystonia and ataxia without epilepsy, paroxysmal exertion-induced dystonia). The aim of our study was to provide a comprehensive overview of GLUT1DS in a French cohort. Methods 265 patients were referred to the French national laboratory for molecular screening between July 2006 and January 2012. Mutations in SLC2A1 were detected in 58 patients, with detailed clinical data available in 24, including clinical features with a focus on their epileptic pattern and electroencephalographic findings, biochemical findings and neuroimaging findings. Results 53 point mutations and 5 deletions in SLC2A1 were identified. Most patients (87.5%) exhibited classic phenotype with intellectual deficiency (41.7%), epilepsy (75%) or movement disorder (29%) as initial symptoms at a medium age of 7.5 months, but diagnostic was delayed in most cases (median age at diagnostic 8 years 5 months). Sensitivity to fasting or exertion in combination with those 3 main symptoms were the main differences between mutated and negative patients (p < 0.001). Patients with myoclonic seizures (52%) evolved with more severe intellectual deficiency and movement disorders compared with those with Early Onset Absence Epilepsy (38%). Three patients evolved from a classic phenotype during early childhood to a movement disorder predominant phenotype at a late childhood/adulthood. Conclusions Our data confirm that the classic phenotype is the most frequent in GLUT1DS. Myoclonic seizures are a distinctive feature of severe forms. However a great variability among patients and overlapping through life from milder classic phenotype to paroxysmal-prominent- movement-disorder phenotype are possible, thus making it difficult to identify definite genotype–phenotype correlations.

The type I interferon system is integral to human antiviral immunity. However, inappropriate stimulation or defective negative regulation of this system can lead to inflammatory disease. We sought to determine the molecular basis of genetically uncharacterized cases of the type I interferonopathy Aicardi-Goutières syndrome, and of other patients with undefined neurological and immunological phenotypes also demonstrating an upregulated type I interferon response. We found that heterozygous mutations in the cytosolic double-stranded RNA receptor gene IFIH1 (MDA5) cause a spectrum of neuro-immunological features consistently associated with an enhanced interferon state. Cellular and biochemical assays indicate that these mutations confer a gain-of-function - so that mutant IFIH1 binds RNA more avidly, leading to increased baseline and ligand-induced interferon signaling. Our results demonstrate that aberrant sensing of nucleic acids can cause immune upregulation.

Cerebral palsy (CP), defined as a group of nonprogressive disorders of movement and posture, is the most common cause of severe neurodisability in children. Understanding its physiopathology is crucial to developing some protective strategies. Interruption of oxygen supply to the fetus or brain asphyxia was classically considered to be the main causal factor explaining later CP. However several ante-, peri-, and postnatal factors could be involved in the origins of CP syndromes. Congenital malformations are rarely identified. CP is most often the result of environmental factors, which might interact with genetic vulnerabilities, and could be severe enough to cause the destructive injuries visible with standard imaging (i.e., ultrasonographic study or MRI), predominantly in the white matter in preterm infants and in the gray matter and the brainstem nuclei in full-term newborns. Moreover they act on an immature brain and could alter the remarkable series of developmental events. Biochemical key factors originating in cell death or cell process loss, observed in hypoxic-ischemic as well as inflammatory conditions, are excessive production of proinflammatory cytokines, oxidative stress, maternal growth factor deprivation, extracellular matrix modifications, and excessive release of glutamate, triggering the excitotoxic cascade. Only two strategies have succeeded in decreasing CP in 2-year-old children: hypothermia in full-term newborns with moderate neonatal encephalopathy and administration of magnesium sulfate to mothers in preterm labor.

Cerebral palsy (CP), defined as a group of nonprogressive disorders of movement and posture, is the most common cause of severe neurodisability in children. Understanding its physiopathology is crucial to developing some protective strategies. Interruption of oxygen supply to the fetus or brain asphyxia was classically considered to be the main causal factor explaining later CP. However several ante-, peri-, and postnatal factors could be involved in the origins of CP syndromes. Congenital malformations are rarely identified. CP is most often the result of environmental factors, which might interact with genetic vulnerabilities, and could be severe enough to cause the destructive injuries visible with standard imaging (i.e., ultrasonographic study or MRI), predominantly in the white matter in preterm infants and in the gray matter and the brainstem nuclei in full-term newborns. Moreover they act on an immature brain and could alter the remarkable series of developmental events. Biochemical key factors originating in cell death or cell process loss, observed in hypoxic-ischemic as well as inflammatory conditions, are excessive production of proinflammatory cytokines, oxidative stress, maternal growth factor deprivation, extracellular matrix modifications, and excessive release of glutamate, triggering the excitotoxic cascade. Only two strategies have succeeded in decreasing CP in 2-year-old children: hypothermia in full-term newborns with moderate neonatal encephalopathy and administration of magnesium sulfate to mothers in preterm labor.

Focal arterial infarction in the full-term newborn is an important cause of acquired cerebral lesions in the perinatal period. Clinical motor seizures, most often unifocal, are the nearly constant disclosing symptom confirmed by focal EEG abnormalities. A multifactorial physiopathology is usual, including genetic and perinatal environmental factors. In the past decade, various acquired or genetic thrombophilias have been discussed as risk factors. For several of the involved mechanisms, the excitotoxic cascade could represent a common final pathway leading to neuronal cell death. Early magnetic resonance imaging studies and EEG help to identify the newborns with strokes who are likely to develop hemiplegia and disabilities at school. Protection of the human fetal brain remains difficult, since the triggering factor initiating the excitotoxic cascade is rarely observed. Treatment of seizures is nevertheless necessary, because it seems that they accelerate anoxia-induced neuronal death in animal models of focal hypoxic ischemia.