Sonia Rodriguez and her husband Cesar were overjoyed when they found out they were going to be parents. Like most married couples, they were ready to start a new chapter in their lives when the unthinkable happened. Doctors informed them that their son, Maximiliano, would be born with a congenital heart defect called Hypoplastic Left Heart Syndrome. HLHS is a rare congenital heart defect in which the left ventricle of the heart is severely underdeveloped.

“Basically my son was born with half a heart,” Sonia explained. “The right ventricle (the one he had) sends oxygen blood flow to his lungs and the left ventricle (the one he didn’t have) sends blood flow to the body.”

Congenital heart defects develop due to the way in which a baby’s heart forms. "Congenital" means that the heart problem develops before the baby is born or at birth. Most congenital heart defects affect how blood flows through the heart or through the blood vessels near the heart. Some defects may cause blood to flow in a pattern that is not normal. Others can completely or partially block blood flow.

Between January 1996 and December 2005 researchers examined the medical records of nearly 20,000 African-American, Latino and white infants born with congenital heart defects in Texas. The study concludes that Latino infants were more likely than white infants to die if they were born without a pulmonary valve opening in the heart.

There are many different types of congenital heart defects. They can be fairly simple, such as a hole between the chambers of the heart or a heart valve that has not formed properly. Others are more serious and complex, such as a missing heart valve or heart chamber.

The causes of congenital hearts defects are ...