[The involvement of myelin proteins in hereditary neuropathies]

Hereditary sensoro-motor neuropathies such as Charcot-Marie-Tooth disease (CMT) form a heterogeneous group including some genetic conditions whose clinical manifestations differ in severity within a group or even within a sub-group. Diagnosis is based on the clinical, electrophysiological and pathological findings along with a genetic analysis. The current classification of CMT encompasses the clinical signs, mode of transmission, genomic localization and identification of the proteins actually involved. Several authors have identified the mutations on genes coding for proteins of peripheral myelin in CMT patients. Recent advances in molecular genetics have thrown more light on the differences between phenotypes within a sub-group, and have established genotype-phenotype relationships. It has been shown recently that the severity of the clinical signs depends on the nature and site of various mutations affecting the genes coding for certain myelin proteins. These mutations give rise to "dominant negative effects" or "mutations with loss of function of the allele". These observations may be extended to other proteins as many of them belong to the super family of immunoglobulins and have similar structures. In this study, we present a review of the literature focussing on the principal myelin proteins and the genomic modifications observed in patients with CMT.