Genes, calcium and modifying factors in hypertrophic cardiomyopathy.

1. Familial hypertrophic cardiomyopathy (FHC) is a primary disorder of the myocardium characterized by remarkable diversity in clinical presentations, ranging from no symptoms to severe heart failure and sudden cardiac death. 2. Over the past 15 years, at least 11 genes have been identified, defects of which cause FHC. Most of these genes encode proteins that comprise the basic contractile unit of the heart (i.e. the sarcomere). 3. Genetic studies are now beginning to have a major impact on the diagnosis in FHC, as well as in guiding treatment and preventative strategies. Although much is known about which genes cause disease, relatively little is known about the molecular steps leading from the gene defect to the clinical phenotype and what factors modify the expression of the mutant genes. 4. Concurrent studies in cell culture and animal models of FHC are now beginning to shed light on the signalling pathways involved in FHC and the role of both environmental and genetic modifying factors. Calcium dysregulation appears to be important in the pathogenesis of FHC. 5. Understanding these basic molecular mechanisms will ultimately improve our knowledge of the basic biology of heart muscle function and will therefore provide new avenues for diagnosis and treatment not only for FHC, but also for a range of human cardiovascular diseases.