We demonstrate that familial hypertrophic cardiomyopathy (FHC), an autosomal dominant disorder of heart muscle, is a genetically heterogeneous disease. The locus responsible for FHC in members of one large kindred was recently mapped to chromosome 14q11-12 (FHC-1). We have characterized three additional unrelated families in which the gene for FHC segregates as an autosomal dominant trait to determine if these disease loci also map to FHC-1. All family members were clinically studied by physical examination, electrocardiogram, and two-dimensional echocardiography. Genetic studies were performed using DNA probes which are derived from loci that are closely linked to FHC-1. In one family the genetic defect maps to the previously identified FHC-1 locus. However, the loci responsible for FHC in two other families were not linked to FHC-1. We conclude that FHC can be caused by defects in at least two loci and is a genetically heterogeneous disorder. (J. Clin. Invest. 1990. 86:993-999.)

Nucleotide sequences necessary to direct

We conclude that RNase protection is a sensitive method for screening for mutations within the beta-cardiac MHC gene. Further, mutations in the noncoding regions of the beta-MHC gene and mutations in the alpha-cardiac MHC gene are not a common cause of FHC. Negative RNase protection assays of affected individuals suggest that their FHC is due to mutations at other loci.