Hereditary motor and sensory neuropathy with absence of large myelinated fibers due to absence of large neurons in dorsal root ganglia and anterior horns, clinically associated with deafness, mental retardation, and epilepsy(HMSN-ADM)

Hereditary motor and sensory neuropathy (HMSN) with autosomal recessive inh eritance represents a genetically heterogeneous group of disorders with var iable clinical, pathologic and electrophysiologic manifestations. A new var iant of autosomal recessive HMSN, clinically defined by sensorimotor polyne uropathy associated with deafness and mental retardation, has recently been described. We report on the first autopsy case with this type of HMSN: a g irl of non-consanguineous parents with a presumably autosomal recessive typ e of motor and sensory neuropathy clinically associated with deafness, ment al retardation, and epilepsy. The autopsy showed complete absence of large myelinated fibers in peripheral motor and sensory nerves corresponding to a lack of large neurons in dorsal root ganglia and anterior horns of the spi nal cord, moderate neurogenic muscle atrophy, and nearly complete absence o f neurons in the dentate nucleus of the cerebellum. Molecular genetic analy ses in our case revealed neither genetic alterations in the survival motor neuron gene nor in the PMP-22 gene.