[Clinical, pathologic and molecular genetic studies of patients with hereditary motor and sensory neuropathy (HMSN)].

Clinical, pathologic and molecular genetic studies of Japanese HMSN patients were reported. Among 26 HMSN I probands tested, the PMP22 gene region was duplicated in 18 (69%). A proband of HNPP, whose PMP22 gene region was deleted, was described. A proband with HMSN I was found to have a mutant allele that caused a substitution of arginine for glycine at amino acid 93 of PMP22. The mutation was located in the transmembrane portion of PMP22. The patient's sural nerve showed decrease of large myelinated fibers and frequent segmental demyelination and remyelination. A family with HMSN IB was found to have a mutant allele that caused a substitution of histidine for arginine at amino acid 98 of Po. The mutation was located in the extracellular domain of Po. The sural nerve from a proband showed uncompaction of major dense lines, wide-spaced major dense lines, and thin myelin sheath relative to axon size. One family of HMSN X with a mutant allele that caused a substitution of leucine for serine at amino acid 26 of Cx32 was found. The mutation was located in the fist transmembrane portion of Cx32. A variety of genetic abnormalities, probably underlying pathologic changes of the peripheral nerve, found among Caucasians were also noticed among Japanese.