VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved residues within the C terminus of the VAMP2 SNARE motif. Affected individuals carrying de novo non-synonymous variants involving the C-terminal region presented a more severe phenotype with additional neurological features, including central visual impairment, hyperkinetic movement disorder, and epilepsy or electroencephalography abnormalities. Reconstituted fusion involving a lipid-mixing assay indicated impairment in vesicle fusion as one of the possible associated disease mechanisms. The genetic synaptopathy caused by VAMP2 de novo mutations highlights the key roles of this gene in human brain development and function.

See Karakaya and Wirth (doi:10.1093/brain/awz273) for a scientific commentary on this article. Neurofascin (NFASC) isoforms are immunoglobulin cell adhesion molecules involved in node of Ranvier assembly. Efthymiou et al. identify biallelic NFASC variants in ten unrelated patients with a neurodevelopmental disorder characterized by variable degrees of central and peripheral involvement. Abnormal expression of Nfasc155 is accompanied by severe loss of myelinated fibres.

BackgroundKrabbe disease (KD) or globoid cell leukodystrophy is an autosomal recessive lysosomal disorder, which affects metabolic and neurologic systems. This pathology has different forms. Infantile onset is about 85 % to 90 % of individuals with Krabbe disease. Disorder’s onset is characterized, in early childhood, by hyperirritability, psychomotor deterioration associated to episodes of fever. To date, all reported cases have been attributed to mutations in galactosylceramidase gene (GALC gene) that encodes an enzyme which degrades galactosyl-sphingolipids (galactosylceramide, psychosine), essential in myelin production. A child compounded with two new mutations in the GALC gene was detected.Case presentationAn eleven month old male child of Moroccan origin presented to our genetic consultation with severe symptoms that included hypotonia, fever, vision loss and feeding difficulties. He was suffering from the 4th month of life. Krabbe disease was suspected. Galactocerebrosidase deficiency was confirmed by biochemical analysis. DNA sequencing revealed a novel heterozygous compound mutation in GALC gene. The child was compounded with two mutations c.860G > A; p.Cys287Tyr and c.1622G > A; p.Trp541*.ConclusionThese new mutations could affect GALC structure and therefore its function. The identification of these mutations and their associated phenotypes are important to predict the prognosis and to confer to families an adequate genetic counseling.

TAF8 is part of the transcription factor II D complex, composed of the TATA-binding protein and 13 TATA-binding protein–associated factors (TAFs). Transcription factor II D is the first general transcription factor recruited at promoters to assemble the RNA polymerase II preinitiation complex. So far disorders related to variants in 5 of the 13 subunits of human transcription factor II D have been described. Recently, a child with a homozygous c.781-1G>A mutation in TAF8 has been reported. Here we describe seven further patients with mutations in TAF8 and thereby confirm the TAF8 related disorder. In two sibling patients, we identified two novel compound heterozygous TAF8 splice site mutations, c.45+4A > G and c.489G>A, which cause aberrant splicing as well as reduced expression and mislocalization of TAF8. In five further patients, the previously described c.781-1G > A mutation was present on both alleles. The clinical phenotype associated with the different TAF8 mutations is characterized by severe psychomotor retardation with almost absent development, feeding problems, microcephaly, growth retardation, spasticity and epilepsy. Cerebral imaging showed hypomyelination, a thin corpus callosum and brain atrophy. Moreover, repeated imaging in the sibling pair demonstrated progressive cerebral and cerebellar atrophy. Consistently, reduced N-acetylaspartate, a marker of neuronal viability, was observed on magnetic resonance spectroscopy. Further review of the literature shows that mutations causing a reduced expression of transcription factor II D subunits have an overlapping phenotype of microcephaly, developmental delay and intellectual disability. Although transcription factor II D plays an important role in RNA polymerase II transcription in all cells and tissues, the symptoms associated with such defects are almost exclusively neurological. This might indicate a specific vulnerability of neuronal tissue to widespread deregulation of gene expression as also seen in Rett syndrome or Cornelia de Lange syndrome.

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ObjectivesX-linked adrenoleukodystrophy is a neurodegenerative disorder caused by mutations in the ABCD1 gene. Adrenomyeloneuropathy and childhood cerebral Adrenoleukodystrophy are the most common phenotypes. This paper focuses on a descriptive study of the first program of diagnosis, treatment, and follow-up of this disease in Morocco.ResultsWe developed three protocols of X-linked Adrenoleukodystrophy management: general protocol, asymptomatic protocol, and heterozygous protocol. Over a period of 5 years, we recruited eight families with 16 patients. Clinically, the presentation is primary adrenal insufficiency and behavioral changes. All patients had elevated levels of very long fatty acids. This is the first study of X-linked adrenoleukodystrophy in Morocco. It shows the importance of this metabolic disease and broadens perspectives in terms of its diagnosis and its treatment.

Background Tay-Sachs disease (TSD) is a rare autosomalrecessive genetic disorder characterized by progressive destruction of nerve cells in the brain and spinal cord. It is caused by genetic variations in the HEXA gene leading to a deficiency of β hexosaminidase A (HEXA) isoenzyme activity. This study aimed to identify causative gene variants in 3 unrelated consanguineous families presented with TSD from Pakistan and Morocco. Methods Detailed clinical investigations were carried out on probands in 3 unrelated consanguineous families of Pakistani and Moroccan origin. Targeted gene sequencing and Whole Exome Sequencing (WES) were performed for variant identification. Candidate variants were checked for co-segregation with the phenotype using Sanger sequencing. Public databases including ExAC, GnomAD, dbSNP and the 1,000 Genome Project were searched to determine frequencies of the alleles. Conservation of the missense variants was ensured by aligning orthologous protein sequences from diverse vertebrate species. Results We report on 3 children presented with Tay-Sachs Disease. The β hexosaminidaseA enzyme activity was reduced in the Pakistani patient in one of the pedigrees. Genetic testing revealed 2 novel homozygous variants (p.Asp386Alafs*13 and p.Trp266Gly) in the gene HEXA in Pakistani and Moroccan patients respectively.The third family of Pakistani origin revealed a previously reported variant (p.Tyr427Ilefs*5) in HEXA. p.Tyr427Ilefs*5 is the most commonly occurring pathogenic variationin Ashkenazi but was not reported in Pakistani population. Conclusion Our study further expands the ethnic and mutational spectrum of Tay-Sachs disease emphasizing the usefulness of WES as a powerful diagnostic tool where enzymatic activity is not performed for Tay-Sachs disease. The study recommends targeted screening for these mutations (p.Tyr427Ilefs5) for cost effective testing of TSD patients. Further, the study would assist in carrier testing and prenatal diagnosis of the affected families.

Down syndrome and autism spectrum disorder can be combined at the child attained; this dual diagnosis is stressful for the parents and is often overlooked by the health and education professionals of these patients. Through three observations collected at the consultation of dysmorphology of the Children's Hospital of Rabat (CHR), this article is illustrated with the details of this association, the clarification of the data of this double diagnosis and the recommendations of good practices for the screening and early management of ASD in this population of children with special needs. The 1 st case: A boy, born on 02/06/2014, unique of his family, is followed for DS. The diagnosis of DS was made at birth and confirmed by the karyotype; para-clinical assessment revealed congenital hypothyroidism (CH) treated with thyroid hormones and without identification of other congenital anomalies; the 2 nd case: A boy, the elder of a sibling of 4, was born on 22/12/2010, the diagnosis of DS was retained from birth, the balance did not objectify congenital pathology; the 3 rd case: A girl was born on 03/12/2009, consanguineous relative, hypotonic, eupneic, eutrophic; a mal-formative assessment on a trisomy 47, XX, +21 karyotype was realized. Diagnosis with PEP3 and CARS shows severe autistic spectrum disorder for all three patients. In the light of these three observations and of the medical literature, the authors stress the importance of screening for precursor signs in the first year of life for early stimulation by parents and neuropsycho-educational rehabilitation, in order to ensure adequate better development of brain plasticity and thus reduce parental stress and complications related to this dual diagnosis.