Haplotypes across the β and αMHC loci associated with the βMHC Ala797Thr mutation. The disease-associated haplotype in representative subsets of families Ped101, Ped104, Ped110, Ped124, Ped131, and Ped138, as well as the assumed haplotype of individuals SB902, SB983, and SB995, bearing the Ala797Thr mutation are boxed. The marker loci used in haplotype construction, covering a distance ⩾8.8 cM, are indicated to the left of the subsets, in centromeric-telomeric order, from top to bottom. The frequencies (white/mixed ancestry) of the alleles of the markers genotyped in the control subpopulations, listed in the order of marker-allele number, are as follows: D14S50—1 (.00/.02), 2 (.01/.00), 3 (.05/.09), 4 (.28/.26), 5 (.21/.18), 6 (.11/.11), 7 (.20/.24), 8 (.13/.08), 9 (.01/.01), and 10 (.00/.01); MYH7 5′UTR—1 (.01/.06), 2 (.03/.05), 3 (.15/.08), 4 (.38/.21), 5 (.32/.28), 6 (.11/.23), and 7 (.00/.09); MYH6—1 (.01/.00), 2 (.01/.00), 3 (.01/.00), 4 (.03/.04), 5 (.01/.00), 6 (.01/.06), 7 (.04/.01), 8 (.07/.04), 9 (.13/.13), 10 (.15/.17), 11, (.32/.21), 12 (.07/.15), 13 (.05/.06), 14 (.04/.07), 15 (.04/.04), and 16 (.01/.02); and D14S64—1 (.02/.01), 2 (.12/.08), 3 (.12/.15), 4 (.29/.06), 5 (.32/.11), 6 (.10/.36), 7 (.02/.14), 8 (.01/.07), and 10 (.00/.02). The allele frequencies at D14S283 and D14S264 were not determined in the control subpopulation groups. MYH7 = βMHC; MYH6 = αMHC; A = alanine; T = threonine.