Erbliche Polyneuropathien

Hereditary motor and sensory neuropathies (HMSN), or Charcot-Marie-Tooth (CMT) disease are labels for a set of congenital diseases with peripheral neuropathy as hallmark and without significant involvement of other organ systems. Recently, molecular genetic methods have become available as diagnostic tool in addition to clinical and electrophysiological investigation. Nerve conduction studies are most important to diagnose CMT and to subdivide them into the two most important categories: HMSN I or CMT1 stands for the demyelinating type of neuropathies with marked slowing of nerve conduction velocity (NCV, lower than 38 m/s for the median nerve). HMSN II or CMT2 comprises cases with normal or near normal NCV but pronounced amplitude reduction of compound muscle action potentials. There are also additional hereditary neuropathies like those with liability to pressure palsy (HNPP) and others with intermediate NCV. A detailed family history and detailed electrophysiological studies (NCV) are the basis on which a molecular genetic study may be requested. At present, the following genes can be investigated on a clinical routine basis: PMP-22 duplication and deletion, myelin protein zero (all autosomal dominant), Connexin 32 (x-chromosomal dominant).