Hereditary motor and sensory neuropathies in Swedish children. I. Prevalence and distribution by disability groups.

The prevalence of hereditary motor and sensory neuropathies (HMSN) and their distribution according to the severity of the disability were studied in a population-based series of Swedish children 2-15 years old. The prevalence per 100 000 of total peroneal muscle atrophies was 21.6 and of all clinical HMSN 19.0 Among HMSN, de- and remyelinating types (HMSN I) constituted 8 per 100000 and neuronal-axonal types (HMSN II) 11. Eighteen of the 21 HMSN I cases and 26 of the 29 HMSN II were considered to represent an autosomal dominant mode of inheritance. Ten per cent of all children were severely, 70% moderately and 20% mildly disabled. All the severely affected children belonged to the HMSN I group and 9 of the 10 mildly affected to HMSN II.