Mouse research provides new insight into formation of the embryonic heart and the genetic basis of congenital defects, according to an article in the July 22nd issue of Nature Medicine.

The discovery changes the fundamental understanding of how hearts are formed, said John A. McDonald, M.D., Ph.D., project leader. "We now have the potential to look at genes in patients who have these heart defects and see if they're abnormal," said McDonald.

McDonald began looking into the role of hyaluronan in disease and health in 1996. His research team discovered the family of genes responsible for production of the polysaccharide. With use of knockout gene techniques, the team deactivated the principal gene in mice. They found that when hyaluronan is absent, the regions that form the septum and valves in developing hearts are absent, too.

In recent work, the group has shown that hyaluronan communicates with a family of receptors called ErbB to play a critical role in formation of heart valves.

"You need both hyaluronan and the ErbB system to build a normal heart," McDonald said. "That was really a surprise."

The next step for the researchers, according to McDonald, is to identify precisely how the polysaccharide activates the ErbB receptor family. They want to find out if it plays a wider role in the formation of other organs or organ systems in the body.

It may also be possible to develop tests that would indicate whether a given patient's congenital cardiac anomaly is genetic in origin or not.