Absence of major deletions or rearrangements of cardiac myosin heavy chain genes in familial hypertrophie cardiomyopathy

Familial hypertrophic cardiomyopathy can be caused by mutation of cardiac myosin heavy chain genes. We demonstrate that major deletions or other structural rearrangements of the cardiac myosin heavy chain locus are not responsible for familial hypertrophic cardiomyopathy in most affected individuals. Cell lines from unrelated affected Individuals with familial hypertrophic cardiomyopathy were analyzed, 47 by fluorescent in situ hybridization and 20 by Southern blotting with α- and β-cardiac myosin heavy chain probes. All cell lines contain two copies each of the α-and β-cardiac myosin heavy chain genes, and no rearrangements were detected. We therefore predict that missense mutations are the predominant cardiac myosin heavy chain defects that cause familial hypertrophic cardiomyopathy.