GENE FOR HEREDITARY NEUROPATHY WITH LIABILITY TO PRESSURE PALSIES (HNPP) MAPS TO CHROMOSOME-17 AT OR CLOSE TO THE LOCUS FOR HMSN TYPE-1

Abstract. Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder with an increased susceptibility of peripheral nerves to mechanical lesions resulting in transient nerve palsies. Many carriers remain asymptomatic but can be traced by electrophysiological examination, thereby demonstrating that HNPP is a generalised polyneuropathy. By using highly polymorphic markers linkage analysis was performed in a large family with HNPP. This resulted in a maximum lod score of 4.20 at theta = 0. 10 with D17S520. Three-point linkage suggests that the gene for HNPP is located on chromosome 17 in the region between D17S250 (q11.2-q12) and D17S520 (p12), a region that has recently been shown to encompass a locus for another hereditary neuropathy, hereditary motor and sensory neuropathy type 1 (HMSN type 1). This raises the possibility that HNPP and this form of HMSN type 1 are allelic. In keeping with this speculation is our recent finding that D17S122, another marker from the HMSN type 1 region, displays apparent loss of heterozygosity in this family.