Rare heart defect found to be cause of marathoner's death

This past weekend, a rather brutal marathon was held in Chicago. Brutal, as in the temperature was a boiling 88 degrees during the race. Normally, that's somewhat mild. But, for this time of year and for a long marathon, that temperature makes for unsafe conditions.

One 35 year-old died during the race, and thousands others quit before finishing and many suffered from heat-related problems as well. But, the lone death did not die to to heat exhaustion or another related malady, but from a rare heart condition according to reports this week.

A condition called "mitral valve prolapse" is being blamed in the death of Chad Schieber, although doctors estimate that the birth defect actually affects 2 to 5 percent of the population -- which is millions of people. Unfortunately, the condition is generally undiagnosed unless observed during a stethoscope exam, or in this unfortunate case, a fatality possibly brought on by the running conditions Mr. Schieber faced.