A RADIATION HYBRID MAP OF 15-LOCI ON THE DISTAL LONG ARM OF CHROMOSOME-4, THE REGION CONTAINING THE GENE RESPONSIBLE FOR FACIOSCAPULOHUMERAL MUSCULAR-DYSTROPHY (FSHD)

A physical map of 4q35 was constructed through radiation hybrid analys is of 134 clones generated from the cell line HHW416, a chromosome 4-o nly human-hamster somatic cell hybrid. This subtelomeric region contai ns the as-yet-unidentified gene responsible for facioscapulohumeral mu scular dystrophy. The most likely order of 15 loci within 4q35 was det ermined. The loci ordered on this radiation hybrid map include both ge nes and polymorphic loci, as well as monomorphic loci which cannot be placed on a genetic linkage map. The physical distance spanning these loci was estimated to be approximately 4.5 Mb, by using a kilobase/cen tiray conversion factor derived from 4p16.3 marker analysis through th e same set of radiation hybrids. The comparison of this physical map t o establish genetic maps suggests that this region is smaller than ini tially estimated and that recombination rates are increased near the t elomere.