Neuropathy, Hereditary Motor And Sensory, With Deafness, Mental Retardation, And Absent Sensory Large Myelinated Fibers

Cornell et al. (1984) reported Charcot-Marie-Tooth disease and sensorineural deafness in 3 sons of first-cousin parents of Asiatic Indian descent living in South Africa. Deafness had been recognized in infancy and normal speech never developed. The CMT disease was of a slow nerve conduction type. See 311070 for a syndrome that comprises optic atrophy in addition to nerve deafness and a Charcot-Marie-Tooth-like neuropathy and 118300 for a dominant form of the CMT-deafness syndrome.

The disorder hereditary motor and sensory neuropathy-Lom (HMSNL; 601455) has been described in Bulgarian Gypsies who were originally derived from India. The disorder resembles that described by Cornell et al. (1984) in an Indian family. HMSNL has been mapped to 8q24.

Mancardi et al. (1992) described 2 brothers with hereditary motor and sensory neuropathy with deafness, mental retardation, and absence of large myelinated fibers. In this family, as in that of Cornell et al. (1984), the parents were first cousins. Sabatelli et al. (1998) reported what appears to be the same disorder in 2 brothers, ages 11 and 13, with an early-onset HMSN, deafness, and mental retardation. Electrophysiologic studies showed marked reduction of motor and sensory conduction velocity and absence of sensory action potentials. Sural nerve biopsy, performed in both patients, showed absence of large myelinated fibers with normal density of small myelinated fibers without axonal degeneration. Signs of demyelination were found only in the younger patient. Parental consanguinity was suspected in their family. Sabatelli et al. (1998) proposed that this disorder is an autosomal recessive trait, although all reported cases have been males.