Genetic trigger discovered for common heart problem, mitral valve prolapse

Ever been to a large sporting event, such as a football or baseball game with 60,000 screaming fans? What you don’t hear through the screams is a clicking sound in the chests of about 1,500 of these fans who have a heart valve disease. And it’s likely that one or two of those are sitting in your row.

Many of these people may, during the excitement of the game, feel that something is not right with their heart. But the problem doesn’t seem severe. So they ignore the sensation of feeling faint or weak, and they continue watching the game.

During a checkup with their primary care physician, however, their doctor might hear the “click” inside their chest. That’s a sign of a potential problem with their heart valves. After they follow up with a cardiologist, they are often diagnosed with a common heart valve disease called mitral valve prolapse. Although one of the most common cardiovascular diseases, doctors have not understood the causes of this disease.

I have been studying heart valve disease for over 20 years and initially became interested in heart valves after I learned that members of my own family had suffered from mitral valve prolapse. This led me to work with Roger Markwald, a pioneer in the field of cardiac valve development. Together, we have been part of large collaborative network to study heart valve disorders. One of these international consortiums has now discovered a genetic cause of mitral valve prolapse.

What is mitral valve prolapse?

The heart is a complicated organ, and there are many things that can go awry. In mitral valve prolapse, the two mitral valve leaflets, or flaps, are located on the left side of your heart and are positioned between the left atrium and left ventricle. These valves function as one-way doors, enabling blood flow in only one direction.

In patients with mitral valve prolapse, the doors become warped and can’t quite close all the way. As a result, blood can flow back into the left atrium and not out to the rest of the body where it should be going. This is called regurgitation. The more regurgitation a person has, the higher the risk of additional complications, including death. The condition affects one in 40 people and is one of the most common cardiovascular diseases worldwide.

Surgery to repair the mitral valve is the fastest-growing cardiovascular intervention in the United States, increasing by more than 40% since 2011.

Embryonic origins of disease

While mitral valve prolapse is common, doctors have not known its causes. It wasn’t until today that I and my colleagues reported a genetic and biological trigger for the disease.