Charcot-Marie-Tooth disease type 2 associated with mutation of the myelin protein zero gene.
ABSTRACT Charcot-Marie-Tooth disease (CMT), or hereditary motor and sensory neuropathy (HMSN), is a clinically and genetically heterogeneous condition. Mutations of the myelin protein zero (MPZ) gene have been associated with CMT1B, Dejerine-Sottas disease, and congenital hypomyelination, which are inherited demyelinating neuropathies characterized by different clinical severity. HMSN type II (HMSN II) or CMT2, the axonal form of CMT, is genetically heterogeneous. Linkage to 1p35-p36 (CMT2A), 3q (CMT2B), and 7p (CMT2D) chromosomes has been reported in the disease; however, most HMSN II families do not link to any of the reported loci. In a large HMSN II Sardinian family, we found a missense mutation in the chromosome 1q MPZ gene. This Ser44Phe mutation was located in exon 2 and was present in the heterozygous state in all affected individuals. This is the first example of an HMSN II family showing an MPZ point mutation. The MPZ gene Ser44Phe mutation found in the HMSN II family presented in this study suggests that genetic analysis of HMSN II families should also include the MPZ gene, previously not considered to be involved in the axonal form of HMSN.
Article: Charcot‐Marie‐Tooth Disease Type 2[Show abstract] [Hide abstract]
ABSTRACT: No unique genes have yet been found for CMT2, but both Cx32 and P0 appear to contribute to the phenotype. Not surprisingly, CMT2 is likely to display much more genetic heterogeneity than CMT1. However, it is also likely continue to challenge previous concepts on classification and relationship of traditional inherited phenotypes in neurology. Future work on CMT2 should produce insight not only into the cellular interactions of the peripheral nerve especially Schwann cell and axon relationships, but also into idiopathic neuropathy.Annals of the New York Academy of Sciences 02/2006; 883(1):42 - 46. · 4.38 Impact Factor
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ABSTRACT: The relationship between dysmyelination and the progression of neuropathy in Charcot-Marie-Tooth (CMT) hereditary polyneuropathy is unclear. Mice heterozygously deficient for the myelin protein P0 gene (P0+/-) are indistinguishable from wild-type (WT) at birth and then develop a slowly progressing demyelinating neuropathy reminiscent of CMT Type 1b. Accumulating evidence suggests that impulse conduction can become lethal to acutely demyelinated central and peripheral axons. Here we investigated the vulnerability of motor axons to long-lasting, high-frequency repetitive stimulation (RS) in P0+/- mice as compared to WT littermates at 7, 12, and 20months of age. RS was carried out in interrupted trains of 200Hz trains for 3h. Tibial nerves were stimulated at the ankle while the evoked compound muscle action potentials (CMAPs) and the ascending compound nerve action potentials (CNAPs) were recorded from plantar muscles and the sciatic nerve, respectively. In 7-month mice, there was recovery of CMAP and CNAP following RS. When mice were about one year old, electrophysiological recovery following RS was incomplete and in P0+/- also associated with morphological signs of partial Wallerian degeneration. The effect of RS was larger in P0+/- as compared to age-matched WT. When mice were about 2years old, the effect was stronger and became similar between WT and P0+/-. RS was followed by a transient hyperpolarization, which decreased with age and was smaller in P0+/- than in WT. Our data suggest that both aging and the dysmyelinating disease process may contribute to the susceptibility to activity-induced axonal degeneration. It is possible that in aging mice and in P0+/- there is inadequate energy-dependent Na+/K+ pumping, as indicated by the reduced post-stimulation hyperpolarization, which may lead to a lethal Na+ overload in some axons.Experimental Neurology 02/2013; · 4.65 Impact Factor
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ABSTRACT: Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of disorders of the peripheral nervous system, mainly characterized by distal muscle weakness and atrophy leading to motor handicap. With an estimated prevalence of 1 in 2,500, this condition is one of the most commonly inherited neurological disorders. Mutations in more than 30 genes affecting glial and/or neuronal functions have been associated with different forms of CMT leading to a substantial improvement in diagnostics of the disease and in the understanding of implicated pathophysiological mechanisms. However, recent data from systematic genetic screening performed in large cohorts of CMT patients indicated that molecular diagnosis could be established only in ∼50-70% of them, suggesting that additional genes are involved in this disease. In addition to providing an overview of genetic and functional data concerning various CMT forms, this review focuses on recent data generated through the use of highly parallel genetic technologies (SNP chips, sequence capture and next-generation DNA sequencing) in CMT families, and the current and future impact of these technologies on gene discovery and diagnostics of CMTs.Molecular syndromology 11/2012; 3(5):204-14.