HEREDITARY MOTOR AND SENSORY NEUROPATHY WITH DEAFNESS, MENTAL-RETARDATION, AND ABSENCE OF SENSORY LARGE MYELINATED FIBERS - CONFIRMATION OFA NEW ENTITY

We describe two brothers, 11 and 13 years old, respectively, with an e arly-onset hereditary motor and sensory neuropathy, deafness, and ment al retardation, Electrophysiological studies showed marked reduction o f motor and sensory conduction velocity and absence of sensory action potentials, Sural nerve biopsy, performed in both patients, showed abs ence of large myelinated fibers with normal density of small myelinate d fibers without axonal degeneration, Signs of demyelination were foun d only in the younger patient, We suggest that motorsensory neuropathy associated with deafness and mental retardation with absence of large myelinated fibers on sural nerve biopsy represents a distinct clinico pathological entity, which is transmitted in families probably as an a utosomal recessive trait, (C) 1998 Wiley-Liss, Inc.