Epidemiological studies have given numbers to what doctors and families have long observed: The risk of neurodevelopmental delays is tenfold higher for children with moderate to severe congenital heart disease than for other children.

But why?

Over the years, those who study these phenomena have considered several possible reasons. Do the rigors of open-heart surgery so soon after birth play a role? Could heart defects limit nutrients and oxygen needed by the fetus? Or could spontaneous genetic mutations cause congenital problems that affect both the heart and the brain of a child?

Now, the ‘why’ may have been answered by the efforts of the Pediatric Cardiovascular Genetics Consortium, led by a team of Harvard Medical School scientists. In a recent issue of Science the consortium reported exome sequence analyses of more than 1,200 children and their parents and showed that children with both congenital heart disease and neurodevelopmental delays share certain genetic mutations that thwart the normal development of both the heart and the brain.

Using a mathematical model created by co-authors Kaitlin Samocha and Mark Daly of the Analytical and Translational Genetics Unit at Massachusetts General Hospital, the team analyzed mutations in the protein-coding portion of the genomes of children with congenital heart disease that were not present in their parents’ genomes. They found that these children have more of these de novo mutations in genes that are highly expressed in the developing heart, compared to a control cohort of children without congenital heart disease.

The de novo mutations were also found to be more frequent in children with congenital heart disease plus another birth defect, either neurodevelopmental delay or more-subtle abnormalities of finger or ear shape. These findings bolster the case for shared genetic causes of the cardiac and extra-cardiac abnormalities rather than surgeries or environmental factors.

Read More: Sciencedaily