[Source: Medical News Today]
Down syndrome is the most common chromosomal abnormality in humans, involving a third copy of all or part of chromosome 21. In addition to intellectual disability, individuals with Down syndrome have a high risk of congenital heart defects. However, not all people with Down syndrome have them – about half have structurally normal hearts.
The risk of AVSD is higher in children with Down syndrome. An atrioventricular septal defect (AVSD) means that the central region of the heart separating the atria from the ventricles has failed to form properly.
Image credit: National Center on Birth Defects and Developmental Disabilities
Geneticists have been learning about the causes of congenital heart defects by studying people with Down syndrome. The high risk for congenital heart defects in this group provides a tool to identify changes in genes, both on and off chromosome 21, which are involved in abnormal heart development.