SummaryCharcot-Marie-Tooth (CMT) disease constitutes a clinically and genetically heterogeneous group of hereditary neuropathies characterized by progressive muscular and sensory loss in the distal extremities with chronic distal weakness, deformation of the feet, and loss of deep tendon reflexes. CMT4H is an autosomal recessive demyelinating subtype of CMT, due to mutations in FGD4/FRABIN, for which nine mutations are described to date. In this study, we describe three patients from a consanguineous Tunisian family, presenting with severe, early onset, slowly progressive, autosomal recessive demyelinating CMT, complicated by mild to severe kyphoscoliosis, consistent with CMT4H. In these patients, we report the identification of a novel homozygous frameshift mutation in FGD4: c.514_515insG; p.Ala172Glyfs * 27.Our study reports the first mutation identified in FGD4 in Tunisian patients affected with CMT. It further confirms the important clinical heterogeneity observed in patients with mutations in FGD4 and the lack of phenotype/genotype correlations in CMT4H. Our results suggest that FGD4 should be screened in other early-onset CMT subtypes, regardless of the severity of the phenotype, and particularly in patients of consanguineous descent. In Tunisians, as in other populations with high consanguinity rates, screening of genes responsible for rare autosomal recessive CMT subtypes should be prioritized.

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l-2-Hydroxyglutaric (l-2-HG) aciduria is a rare inherited metabolic disease usually observed in children. Patients present a very slowly progressive deterioration with cerebellar ataxia, mild or severe mental retardation, and various other clinical signs including extrapyramidal and pyramidal symptoms, and seizures Goffette et al. [1]. This leukencephalopathy was first described in 1980 Duran et al. [2]. Brain magnetic resonance imaging (MRI) demonstrates nonspecific subcortical white matter (WM) loss, cerebellar atrophy and changes in dentate nuclei and putamen Steenweg et al. [3]. The diagnosis is highlighted by increased levels of l-2-HG in body fluids such as urine and cerebrospinal fluid.The purpose of this study is to retrospectively describe the brain MRI features in l-2-HG aciduria.

The impairment of alternative splicing of exon 19 and the lack of a part of the proteasome signal due to c.2788insG mutation could disrupt the dynamic regulation of isoform levels especially hCDKL5_5 and hCDKL5_1 during pre and postnatal neurodevelopment and then could cause pathogenic phenotype. Signal peptidase I serine active site seems to modulate hCDKL5_5 movements between nucleus and cytoplasm. We noticed that the resulting phenotypes from truncated mutations among the C-terminal domain of hCDKL5 are almost similar and are always severe.