AHA: New Report Explores Genes Behind Congenital Heart Disease

THURSDAY, Sept. 27, 2018 (American Heart Association) -- Genetics are at the core of some congenital heart defects, and a just-released scientific statement could help guide doctors in new information and testing techniques that not only could help patients but also their families.

The report from the American Heart Association, published Sept. 27 in the journal Circulation, provides an update on advancements in the world of genetics and congenital heart disease, a term used to describe defects or abnormalities that occur when the heart doesn't develop normally before birth.

"In the last 10 years, there have been many important new scientific ways of investigating genes and identifying genes causing congenital heart disease. This new understanding has changed our whole outlook on how to take care of patients with congenital heart disease," said the statement's lead author, Dr. Mary Ella Pierpont, a pediatrician and a professor of pediatric genetics and metabolism at the University of Minnesota.

The summary covers a broad spectrum of topics and new advancements in genetic conditions, including a phenomenon called copy number variation, or CNV, when the number of copies of a particular gene varies from one person to the next. The statement also offers updated information on new molecular testing techniques and how they apply to congenital heart disease and other congenital anomalies or syndromes.

"If doctors know the cause of their patients' conditions, they can make a better long-term medical management plan, provide better care and the promise of a healthier life," Pierpont said. "For example, certain types of congenital heart disease could be associated with rhythm disturbances, and knowing the gene abnormality can help the physician evaluate for the possibility of arrhythmia."

New genetic testing techniques help pinpoint a prognosis for congenital heart disease, assess risks for the patient's children and other close relatives, and alert doctors to associated medical conditions that may need attention.

The statement helps doctors "think about things in the context of a family, not just the individual in front of you," said Dr. Carolyn Ho, medical director of the Cardiovascular Genetics Center at Brigham and Women's Hospital, and an associate professor at Harvard Medical School.

Ho, who was not involved in writing the report, said "the types of genetic anomalies that underlie congenital heart disease are incredibly diverse, and this statement does a good job of saying which types of genetic testing you can have, based on the broad range of genetic changes and how it can lead to congenital heart disease."

The statement discusses new prenatal gene testing techniques that have emerged in recent years to better inform doctors and parents who may be concerned about the increased risks for women who have congenital heart disease and for their baby.

"The statement is not dogmatic, saying you must or should be tested -- but you do need to be educated so you can make a good decision for yourself and your family," said Dr. Wendy K. Chung, a statement co-author and a clinical and molecular geneticist and professor of pediatrics at Columbia University. "The statement is saying it's important for parents to see professionals who are experienced in the prenatal setting, such as a genetic counselor and/or geneticist."

Newer prenatal tests include non-invasive cell-free DNA testing, which is conducted by blood sample from the mother, and chromosomal microarray, or CMA, testing. Testing is done after an amniocentesis, a procedure which can carry a small risk of miscarriage. The statement says CMA tests are warranted, either prenatally or postnatally, for people with certain types of congenital heart disease.

"The cell-free DNA test can detect some things associated with congenital heart disease, but the chromosome microarray test gives you more information," said Chung. "Looking forward, there are much more powerful technologies that we currently use prenatally in research studies. There's a lot coming down the pike very quickly."

Pierpont agreed, but she expressed concern that key research on congenital heart defects may go unfunded, including studies on how non-cardiac diseases might be associated with congenital heart disease.

"Adult heart disease and cholesterol gets the bulk of the funding in heart disease, but we also need improved research for congenital heart disease," she said. "This paper shows there's a lot happening. It's a very important area for future research."