ASSIGNMENT OF MICROSATELLITE SEQUENCES TO THE REGION DUPLICATED IN CMT1A (17P12) - A USEFUL TOOL FOR DIAGNOSIS

Charcot-Marie-Tooth disease type 1A (CMT1A), the most prevalent form o f the peripheral hereditary neuropathies, has been associated with a d uplication of a genomic segment of 1 . 5 Mb, located in 17p11.2. Recen tly, the same segment has been found to be deleted in patients with an other peripheral neuropathy, hereditary neuropathy with liability to p ressure palsies (HNPP). Highly polymorphic markers are rare in this ar ea, rendering the diagnosis highly dependent either on invasive examin ations (like nerve biopsy) or not totally reliable (like gene dosage). Thus, we used a contig of YACs, including the whole region duplicated in CMT1A, to map highly polymorphic microsatellite loci, designed in Genethon. We showed that four of these loci are located in the duplica ted region, allowing us to propose them as diagnostic markers for CMT1 A and HNPP.