The hereditary neuropathies consist of a large group of conditions that for descriptive purposes are conveniently separable into the hereditary motor and sensory neuropathies, the hereditary sensory and autonomic neuropathies and conditions in which the neuropathy is associated with a generalized metabolic disorder. The hereditary motor neuropathies (spinal muscular atrophies) are discussed elsewhere (see Chapters 116, 117).

Hereditary motor and sensory neuropathies

The hereditary motor and sensory neuropathies comprise a miscellaneous group of disorders in which a number of different clinical patterns are recognizable. Broadly speaking, these are the Charcot–Marie–Tooth (CMT) syndrome, Dejerine–Sottas disease (DSD) and congenital hypomyelination neuropathy (CHN) (Reilly, 2000). In addition, there are two examples of inherited recurrent neuropathy, namely hereditary neuropathy with liability to pressure palsies (HNPP) and hereditary neuralgic amyotrophy (HNA) and a number of other rare but important more complex disorders that deserve consideration.

Charcot–Marie–Tooth disease

Charcot–Marie–Tooth (CMT) disease is divisible into three categories, in two of which, types 1 and 2, the inheritance is autosomal and in the third it is X-linked. CMT disease is the commonest inherited neuropathy with a prevalence of about 20–40:100000 (Dyck et al., 1993).

Charcot–Marie–Tooth disease type 1

CMT1 or type 1 hereditary motor and sensory neuropathy (HMSN I) usually begins in the first decade of life, less often in the second and rarely at later ages. The onset is commonly with difficulty in walking or foot deformity with later involvement of the upper limbs. Variable disability develops during childhood and adolescence following which deterioration is slow or sometimes negligible. Inheritance is most frequently of autosomal dominant pattern, less often autosomal recessive. In dominantly inherited families clinical severity is highly variable (Thomas et al., 1997). Some heterozygous gene carriers may be asymptomatic and others may just display foot deformity. The characteristic clinical features are distal muscle wasting and weakness in the limbs giving rise to a ‘stork leg’ appearance accompanied by atrophy of the small hand muscles. Patients with prominent upper limb postural tremor have been referred to as the Roussy–Lévy syndrome.