Hereditary motor and sensory neuropathy of neuronal type with onset in early childhood.

Eighteen cases of a chronic progressive motor and sensory neuropathy of neuronal type with early onset are described. Based on the presented data and literature reports a condition is distinguished, which is in clinical, genetic and morphological aspects different from autosomal dominant HMSN type II. The condition corresponds to that described by Ouvrier et al. (1981). It shows a congenital or early childhood onset and causes a severe disability usually with wheelchair dependency already in puberty or later in adult life. The condition is probably transmitted by an autosomal recessive gene. Morphological features of biopsied nerves are an extensive loss of large diameter fibres with a shift to smaller diameters in the histogram. Regenerative features are almost absent in contrast to the distinct cluster formation in autosomal dominant HMSN type II. A maturation disturbance of peripheral motor and sensory neurons with a concomitant or secondary process of chronic neuronal degeneration is suggested. One dominantly inherited case in our group with an infantile onset exhibits clinical and morphological features consistent with an autosomal dominant HMSN type II.