After years of "brute force" work at Harvard Medical School, Christine (a.k.a. Kricket) and Jon Seidman made a stunning discovery. They found that all affected members of two families with cardiomyopathy carried a mutation in a gene encoding myosin heavy chain. When expressed, the gene's product works to contract muscles. That breakthrough led to the discovery of more genetic culprits, including cardiac troponin T and alpha tropomyosin, which also function in contraction. The genes encode proteins that also function in contraction.

"At that point, we said, 'Oh, I get it,'" Kricket Seidman recalls. "These are all parts of the muscle contractile apparatus."

And that commonality also pointed to the killer: a genetic problem that leads to patients' inability to properly contract their heart muscles.

"The finding was rather like a birth announcement," Seidman says. "We knew something good was going to happen down the road, but we didn't know precisely what."