The hereditary peripheral neuropathies have been classified based upon clinical characteristics, mode of inheritance, electrophysiologic features, metabolic defect, and subsequently upon specific genetic markers. The primary hereditary neuropathies predominantly or exclusively affect peripheral nerves and produce symptoms of peripheral nerve dysfunction. Other hereditary neuropathies affect both the central and peripheral nervous systems and, in some cases, other organs; in such patients, symptoms related to the peripheral neuropathy may be overshadowed by other manifestations of the disease.
Historically, the primary hereditary neuropathies were designated by eponyms that had the connotation of specific clinical features (eg, Charcot-Marie-Tooth disease or Dejerine-Sottas disease). However, phenotypic variability resulted in substantial diagnostic confusion. The Dyck classification developed in the 1970s helped to define specific types based upon clinical and electrophysiologic features .
- Many of the primary hereditary neuropathies were divided into motor-sensory and sensory–autonomic neuropathies.
- The motor-sensory category was subdivided into types one through seven and the sensory neuropathies into types one through five. Many of these types were further divided into subcategories.
- Additional primary inherited neuropathies not included in this classification include hereditary neuropathy with pressure palsy, hereditary brachial plexopathy, and giant axonal neuropathy. The molecular defects in many of the inherited neuropathies have been identified.
This topic will provide an overview of the hereditary neuropathies. Detailed discussions of the hereditary motor and sensory neuropathies, the hereditary sensory and autonomic neuropathies, and the hereditary neuropathies associated with generalized disorders are found separately. (See "Hereditary primary motor sensory neuropathies, including Charcot-Marie-Tooth disease" and "Hereditary sensory and autonomic neuropathies" and "Hereditary neuropathies associated with generalized disorders".)
HEREDITARY MOTOR AND SENSORY NEUROPATHIES
The main entity in this category, hereditary motor and sensory neuropathy (HMSN), also known as Charcot-Marie-Tooth (CMT) disease, is reviewed here briefly and discussed in detail elsewhere. (See "Hereditary primary motor sensory neuropathies, including Charcot-Marie-Tooth disease".)