Early onset neuropathy in a compound form of Charcot-Marie-Tooth disease

A 2-year-old boy presented with early-onset Charcot-Marie-Tooth disease (CMT). His parents had not been diagnosed previously with CMT, but on careful examination they showed clinical signs of CMT and reduced nerve conduction velocities. Genetic analysis identified the boy as a heterozygote for both a peripheral myelin protein 22 (PMP22) duplication and a mutation in the lipopolysaccharide-induced-tumour-necrosis-factor-alpha-factor(LITAF) gene, whereas each parent only had one mutated CMT gene. This suggests that LITAF mutations can severely affect the CMT phenotype caused by a PMP22 duplicatio

CSTB NULL MUTATION ASSOCIATED WITH MICROCEPHALY, EARLY DEVELOPMENTAL DELAY, AND SEVERE DYSKINESIA

The CSTB gene encodes for cystatin B, an inhibitor of lysosomal cysteine protease (cathepsins B, H, L, and S).(CSTB)-C-1 mutations have been associated with type 1 progressive myoclonic epilepsy, also known as Unverricht-Lundborg (ULD) disease, or Baltic myoclonus.(2,3) A total of 90% of all disease alleles consists of an expansion of at least 30 times of an unstable 12-nucleotide stretch (dodecamer 5-CCCCGCCCCGCG-3) in the CSTB promoter region. Homozygosity for this expansion is considered the founder mutation in the Finnish population. Few other mutations have been described, among these the p.Arg68*, but until now only as compound heterozygous with the dodecamer expansion.(4-6) Expression of the p.Arg68* mutation in vitro indicates that the truncated protein is rapidly degraded, confirming that it is a null mutation.(7) Between the ages of 6 and 16 years, ULD begins with stimulus-sensitive myoclonus and generalized tonic-clonic seizures, which can be worsened by phenytoin, followed by ataxia and slow neurodegeneration. Here we report on the first 2 patients with a homozygous p.Arg68* null mutation

Homozygous Nonsense Mutations in KIAA1279 Are Associated with Malformations of the Central and Enteric Nervous Systems

We identified, by homozygosity mapping, a novel locus on 10q21.3-q22.1 for Goldberg-Shprintzen syndrome (GOSHS) in a consanguineous Moroccan family. Phenotypic features of GOSHS in this inbred family included microcephaly and mental retardation, which are both central nervous system defects, as well as Hirschsprung disease, an enteric nervous system defect. Furthermore, since bilateral generalized polymicogyria was diagnosed in all patients in this family, this feature might also be considered a key feature of the syndrome. We demonstrate that homozygous nonsense mutations in KIAA1279 at 10q22.1, encoding a protein with two tetratrico peptide repeats, underlie this syndromic form of Hirschsprung disease and generalized polymicrogyria, establishing the importance of KIAA1279 in both enteric and central nervous system development