Dominant hereditary inclusion-body myopathy gene (IBM3) maps to chromosomeregion 17p13.1

We recently described an autosomal dominant inclusion-body myopathy charact erized by congenital joint contractures, external ophthalmoplegia, and pred ominantly proximal muscle weakness. A whole-genome scan, performed with 161 polymorphic markers and with DNA from 30 members of one family, indicated strong linkage for markers on chromosome 17p. After analyses with additiona l markers in the region and with DNA from eight additional family members, a maximum LOD score (Z(max)) was detected for marker D17S1303 (Z(max) = 7.3 8; recombination fraction (theta) = 0). Haplotype analyses showed that the locus (Genome Database locus name: IBM3) is flanked distally by marker D17S 945 and proximally by marker D17S969. The positions of cytogenetically loca lized flanking markers suggest that the location of the IBM3 gene is in chr omosome region 17p13.1. Radiation hybrid mapping showed that IBM3 is locate d in a 2-Mb chromosomal region and that the myosin heavy-chain (MHC) gene c luster, consisting of at least six genes, co-localizes to the same region. This localization raises the possibility that one of the MHC genes clustere d in this region may be involved in this disorder.