DELETION IN CHROMOSOME 17P11.2 INCLUDING THE PERIPHERAL MYELIN PROTEIN-22 (PMP-22) GENE IN HEREDITARY NEUROPATHY WITH LIABILITY TO PRESSUREPALSIES

We report the clinical, electrophysiological, and pathological finding s of two unrelated Japanese families with hereditary neuropathy with l iability to pressure palsies (HNPP) and confirm the findings of a dele tion of peripheral myelin protein-22 (PMP-22) gene. Electrophysiologic al studies revealed slowing of nerve conduction velocities of the affe cted nerves. Sural nerve biopsy revealed regions of myelin duplication . The copy numbers of PMP-22 gene was lower than that of normal contro l, suggesting deletion of 17p11.2 including PMP-22 gene. Our results i ndicate that HNPP in these two Japanese families is attributable to de letion of 17p11.2 including PMP-22 gene.