DEMONSTRATION OF A 5TH DISEASE LOCUS IN F AMILIAL HYPERTROPHIC CARDIOMYOPATHY

Hypertrophic cardiomyopathy is familial in about 50% of cases and is t ransmitted in the autosomal dominant mode. The first morbid gene impli cated in the disease was the gene coding the betamyosin heavy chain (b eta MHC) on chromosome 14. However, only 30% of families have this gen etic abnormality. Recently, three new loci have been identified on chr omosomes 1q3, 11p13-q13 and 15q2. In order to determine whether other genes could be implicated in the disease a linkage analysis study was performed in a West Indian family. The method is based on the analysis of the distribution of the disease in the family and the microsatelli te markers. The microsatellites used were those which recognised the 4 loci previously mentioned and 4 new markers situated and arranged wit h respect to known microsatellites. The results show that in the famil y studied, the disease did not concord with the markers of the beta MH C gene or with those recognising the loci on chromosomes 1q3, 11p13-q1 3 and 15q2. There is, therefore, a fifth gene implicated in familial H CM. The heterogeneity of the disease seems even greater than originall y thought.