Reda Ouazzani

Clinical comparison between AVED patients with 744 del A mutation and Friedreich ataxia with GAA expansion in 15 Moroccan families

Fifteen Moroccan families with a phenotype resembling Friedreich Ataxia (FA) were studied. Seven families (13 patients) had the 744 del A mutation in the alpha-tocopherol transfer protein (alpha-TTP) gene, characteristic of ataxia with vitamin E deficiency (AVED). The other eight families (16 patients) had GAA expansions in the first intron of the frataxin gene. The clinical differences between the two groups differed. AVED caused by the 744 del A could be distinguished by head titubation, lower frequency of the neuropathy and slower disease progression, decreased visual activity and retinitis pigmentosa, which has also been associated with a His(101) Gln missense mutation in the alpha-TTP gene. The neurological disorder associated with vitamin E deficiency can be improved by the alpha-tocopherol treatment.

Role of the phosphoinositide phosphatase FIG4 gene in familial epilepsy with polymicrogyria

Objective: The aim of this study was to identify the causal gene in a consanguineous Moroccan family with temporo-occipital polymicrogyria, psychiatric manifestations, and epilepsy, previously mapped to the 6q16–q22 region. Methods: We used exome sequencing and analyzed candidate variants in the 6q16–q22 locus, as well as a rescue assay in Fig4-null mouse fibroblasts and immunohistochemistry of Fig4-null mouse brains. Results: A homozygous missense mutation (p.Asp783Val) in the phosphoinositide phosphatase gene FIG4 was identified. Pathogenicity of the variant was supported by impaired rescue of the enlarged vacuoles in transfected fibroblasts from Fig4-deficient mice. Histologic examination of Fig4-null mouse brain revealed neurodevelopmental impairment in the hippocampus, cortex, and cerebellum as well as impaired cerebellar gyration/foliation reminiscent of human cortical malformations. Conclusions: This study extends the spectrum of phenotypes associated with FIG4 mutations to include cortical malformation associated with seizures and psychiatric manifestations, in addition to the previously described Charcot-Marie-Tooth disease type 4J and Yunis-Varón syndrome.

A homozygous loss-of-function variant in MYH11 in a case with megacystis-microcolon-intestinal hypoperistalsis syndrome

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is characterized by marked dilatation of the bladder and microcolon and decreased intestinal peristalsis. Recent studies indicate that heterozygous variants in ACTG2, which codes for a smooth muscle actin, cause MMIHS. However, such variants do not explain MMIHS cases that show an autosomal recessive mode of inheritance. We performed exome sequencing in a newborn with MMIHS and prune belly phenotype whose parents are consanguineous and identified a homozygous variant (c.3598A>T: p.Lys1200Ter) in MYH11, which codes for the smooth muscle myosin heavy chain. Previous studies showed that loss of Myh11 function in mice causes a bladder and intestinal phenotype that is highly reminiscent of MMIHS. All together, these observations strongly suggest that loss-of-function variants in MYH11 cause MMIHS. The documentation of variants in ACTG2 and MYH11 thus points to the involvement of the contractile apparatus of the smooth muscle in MMIHS. Interestingly, dominant-negative variants in MYH11 have previously been shown to cause thoracic aortic aneurism and dilatation. Different mechanisms of MYH11 disruption may thus lead to distinct patterns of smooth muscle dysfunction.

Mutations in CAPN1 Cause Autosomal-Recessive Hereditary Spastic Paraplegia

Hereditary spastic paraplegia (HSP) is a genetically and clinically heterogeneous disease characterized by spasticity and weakness of the lower limbs with or without additional neurological symptoms. Although more than 70 genes and genetic loci have been implicated in HSP, many families remain genetically undiagnosed, suggesting that other genetic causes of HSP are still to be identified. HSP can be inherited in an autosomal-dominant, autosomal-recessive, or X-linked manner. In the current study, we performed whole-exome sequencing to analyze a total of nine affected individuals in three families with autosomal-recessive HSP. Rare homozygous and compound-heterozygous nonsense, missense, frameshift, and splice-site mutations in CAPN1 were identified in all affected individuals, and sequencing in additional family members confirmed the segregation of these mutations with the disease (spastic paraplegia 76 [SPG76]). CAPN1 encodes calpain 1, a protease that is widely present in the CNS. Calpain 1 is involved in synaptic plasticity, synaptic restructuring, and axon maturation and maintenance. Three models of calpain 1 deficiency were further studied. In Caenorhabditis elegans, loss of calpain 1 function resulted in neuronal and axonal dysfunction and degeneration. Similarly, loss-of-function of the Drosophila melanogaster ortholog calpain B caused locomotor defects and axonal anomalies. Knockdown of calpain 1a, a CAPN1 ortholog in Danio rerio, resulted in abnormal branchiomotor neuron migration and disorganized acetylated-tubulin axonal networks in the brain. The identification of mutations in CAPN1 in HSP expands our understanding of the disease causes and potential mechanisms.

Haplotype study of West European and North African Unverricht-Lundborg chromosomes: evidence for a few founder mutations

Abstract. Unverricht-Lundborg disease (ULD) is a progressive myoclonus epilepsy common in Finland and North Africa, and less common in Western Europe. ULD is mostly caused by expansion of a dodecamer repeat in the cystatin B gene (CSTB) promoter. We performed a haplotype study of ULD chromosomes (ULDc) with the repeat expansion. We included 48 West European Caucasian (WEC) and 47 North African (NA) ULDc. We analysed eight markers flanking CSTB (GT10-D21S1890-D21S1885-D21S2040-D21S1259-CSTB-D21S1912-PFKL-D21S171) and one intragenic variant in the CSTB 3′ UTR (A2575G). We observed a founder effect in most of the NA ULD patients, as 61.7% of the NA ULDc (29/47) shared the same haplotype, A1 (1-1-A-1-6-7), for markers D21S1885-D21S2040-A2575G-D21S1259-D21S1912-PFKL. Moreover, if we considered only the markers D21S1885, D21S2040, A2575G and D21S1259, 43 of the 47 NA ULDc shared the same alleles 1-1-A-1, haplotype A. As previously shown, the WEC ULDc were heterogeneous. However, the Baltic haplotype, A3 (5-1-1-A-1-1), was observed in ten WEC ULDc (20.8%) and the CSTB 3′UTR variant, which we called the Alps variant, was observed in 17 ULDc (35.4%). Finally, as almost all NA patients, like Scandinavian patients, were of the haplotype A, we assumed that there was an ancient common founder effect in NA and Baltic ULD patients. We estimated that the putative most recent common ancestral ULD carrier with this haplotype A must have existed about 2,500 years ago (100–150 generations). Finally, this work provides evidence for the existence of only a small number of founder mutations in ULD.

Autosomal recessive mutilating sensory neuropathy with spastic paraplegia maps to chromosome 5p15.31-14.1.

Autosomal recessive ulcero-mutilating neuropathy with spastic paraplegia is a very rare disease since only few cases were described up to date. We report in this study a consanguineous Moroccan family with four affected males with this syndrome. The disease onset was in early infancy, with spastic paraplegia and sensory loss leading to mutilating acropathy. Electrophysiological studies revealed a severe axonal sensory neuropathy, magnetic resonance imaging ruled out compression of spinal cord and biological investigations showed decreased levels of Apo B, total cholesterol and triglycerides. A genomewide search was conducted in this family and linkage was found to chromosome 5p. Analysis of recombination events and LOD score calculation map the responsible gene in a 25 cM genetic interval between markers D5S2054 and D5S648. A maximum LOD score value of 3.92 was obtained for all markers located in this candidate interval. This study establishes the presence of a locus for autosomal recessive mutilating sensory neuropathy with spastic paraplegia on chromosome 5p15.31–14.1.

A locus for bilateral occipital polymicrogyria maps to chromosome 6q16-q22.

We describe the clinical, radiographic, and genetic features of a large consanguineous Moroccan family in which bilateral occipital polymicrogyria segregated as an autosomal recessive trait. Six affected members of the family had partial complex seizures often associated with behavioral abnormalities. On MRI, three patients had a thickened irregular cortex in the lateral occipital lobes with small gyri. Ahigh-density genome-wide scan with 10,000 SNPs established linkage by homozygosity mapping to a 14-Mb region on chromosome 6q16–q22. Candidate genes by function (TUBE1, GRIK2, GPRC6A, GPR6, NR2E1, MICAL1, and MARCKS) in this locus were screened for mutations.

A Novel GDAP1 Mutation P78L Responsible for CMT4A Disease in Three Moroccan Families

BACKGROUND The gene encoding the ganglioside-induced-differentiation-associated protein 1 (GDAP1) has been associated with both axonal and demyelinating neuropathy. Up to date, 25 mutations in the GDAP1 gene have been reported in patients from different origins. METHODS Three Moroccan families with early onset ARCMT1 and autosomal recessive inheritance were genotyped to test linkage to 8q21.3 and their GDAP1 gene coding exons screened for mutations. RESULTS A novel C233T transversion at codon 78 (P78L) was detected in 6 patients from 3 unrelated families. The mutation was found to be homozygous in two families and compound heterozygous in association with the already reported S194X mutation in one family. The P78L mutation was associated with a common haplotype suggesting a Moroccan founder mutation. The patients had symptoms within the two first years of life and developed common phenotype of CMT4A with evident hoarse-voice in two cases with the longer disease duration. CONCLUSION P78L mutation was associated with a common haplotype suggesting a common ancestor.

Vitamin E deficiency ataxia associated with adenoma

Vitamin E is one of the most important lipid-soluble antioxidant nutrient. Severe vitamin E deficiency (VED) can have a profound effect on the central nervous system. VED causes ataxia and peripheral neuropathy that resembles Friedreichs ataxia. We report here a patient presenting this syndrome, but also a prolactin and FSH adenoma. Both the neurological syndromes and the adenoma regressed after treatment with alpha-tocopherol. Although, the presence of the prolactinoma in this patient may not be related to his vitamin E deficiency, alpha-tocopherol treatment seems to be beneficial and might usefully be tested in patients with hypophyseal secreting other forms of adenoma.

Lymphome T révélé par une mononeuropathie multiple : étude d'un cas avec revue de la littérature

Resume Introduction Les complications nerveuses peripheriques des lymphomes sont rares et rarement inaugurales. Nous rapportons une observation clinique dans laquelle une mononeuropathie multiple (MNM) a revele un lymphome non hodgkinien (LMNH) de type T. Observation Un patient de 32 ans a developpe progressivement une atteinte successive de plusieurs troncs nerveux : le nerf sciatique poplite externe gauche, le nerf median gauche apres un mois et le nerf trijumeau gauche 10 mois plus tard. L’electroneuromyogramme a confirme la presence d’une MNM de type axonal. Devant la presence d’une atteinte systemique extraneurologique, une biopsie osteo-medullaire a ete realisee et a montre un LMNH de type T. La biopsie nerveuse a objective un infiltrat inflammatoire lymphocytaire faisant evoquer un possible mecanisme inflammatoire a l’origine de la neuropathie. Aucune amelioration n’a ete notee apres chimiotherapie. Discussion Ce cas clinique est particulier, d’une part par la rarete de l’association MNM et LMNH et d’autre part, par le caractere revelateur de la MNM. Nous avons pu repertorie dans la litterature 30 cas de neuropathies (polyneuropathies, MNM et mononeuropathies uniques) revelateurs d’un LMNH. Dans la majorite des cas, il s’agissait d’une polyneuropathie axonale chronique. Le lymphome etait le plus souvent de type B, correle a un mauvais pronostic. Tous les mecanismes d’atteinte du systeme nerveux peripherique ont ete observes avec une predominance de la neurolymphomatose.