Occurrence of active demyelinating lesions in children with hereditary motor and sensory neuropathy (HMSN) type I.

In three children with dominant hereditary motor and sensory neuropathy type I, peripheral nerve biopsy showed the classical lesions of segmental demyelination with remyelination and onion bulb formations. In two cases, ultrastructural examination also demonstrated numerous characteristic features of active demyelination. The presence of active demyelinating lesions suggests an autoimmune attack superimposed on the course of a chronic genetic disease.