Genetic causes cardiac disorders

In a previous section we mentioned the significance of myosin filament structure. In nematodes two forms of myosin-II, myosin A and B, are required for proper filament stmcture (Epstein, 1988). The two forms of myosin are expressed at the proper time to allow for correct filament assembly. An accessory protein called paramyosin is also required for correct filament assembly. In vertebrate cardiac muscle, there are also two isoforms of myosin-II a-myosin and p-myosin. The proper ratio of these two proteins is of utmost importance for proper muscle activity. The incorrect synthesis of a- and P-myosins results in a severe cardiac disorder known as hypertrophic cardiomyopathy. Genetic transmission of the disease occurs in about 55% of families. The inherited condition is called familial hypertrophic cardiomyopathy (FHC), and this condition is a leading cause of sudden death in young athletes. 

Alterations in the structure or function of an ion channel caused by mutations in a gene encoding one of the channel s subunits are termed channelopathies. Initially, these abnormalities were associated with cardiac and muscular disorders, but today, it is recognized that channelopathies are responsible for several forms of epilepsy (15,16). Presently, most of the discovered channel mutations appear to be associated with the development of idiopathic generalized epilepsy most partial seizures are believed to be acquired. Minor alterations in gene structure or expression, however, may predispose a given individual to partial seizures. It is estimated that 40% of adult and childhood epilepsy may result from genetic factors. 

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