Cardiomyopathy is a mysterious condition. It is characterized by hypertrophy, or enlarged hearts. An estimated 1 in 500 people have such unexplained hypertrophy. Hypertrophic cardiomyopathy (HCM), as it known in clinical circles, can be silent, meaning that it does not cause any symptoms until it is fatal.

HCM is the number one cause of sudden death in athletes, who otherwise appear to be in the most vibrant health. This abrupt onset gives the disease its mysterious character -- and also adds to its tragedy.

Without better information, researchers for decades assumed that lifestyle factors, including smoking, poor diet, and excessive exercise contributed to this condition. But investigators also knew that cardiomyopathy ran in families. Clearly, genes also played a role.

Thus, beginning in 1980, the Seidmans began hunting for genes in the DNA of susceptible families, genes that might prod the disease to begin its sometimes-fatal progression.