[A case of hereditary pressure-sensitive neuropathy, confirmed by a gene analysis].

A 21-year-old male patient with hereditary pressure-sensitive neuropathy (HPSN) is reported. He had been well and was working as a carpenter until February 6, 1993, when he developed difficulty in raising his left arm and numbness in the radial aspect of his left forearm in the morning. Left musculocutaneous nerve palsy, a left winged-scapula, absence of the left biceps and right Achilles reflexes, and distal dominant nerve conduction delay were positive findings. His father and younger brother showed similar conduction delays. Sural nerve biopsy revealed the presence of tomacula, segmental demyelination and thinly myelinated fibers. Gene analyses of the patient's cultured lymphoblastoid cells disclosed deletion of the marker 6G1 and peripheral myelin protein-22 (PMP-22) gene of a single allele of chromosome 17 in 90% of his intermitotic cells by in situ hybridization, and also a 57% gene dosage of PMP-22 of normal control using Southern blotting. These findings indicate the deletion in 17p11.2 of the genomic DNA of this patient, which is diagnostic for HPSN.