Causes
If part of the endocardial tube gets pinched shut in a region that becomes the future ventricle, hypoplastic heart syndrome will occur. If the pinched part of the endocardial tube is the bulbus-cordis region of the developing heart, hypoplastic RIGHT syndrome will occur. If it is in the ventricle region it will be the LEFT side that is hypoplastic.
There is evidence associating it with Gap junction protein, alpha 1.
Colleagues at Cincinnati Children’s Hospital in Ohio studied 1,500 newborns from 38 children’s hospitals in the United States from the 1990s to 2006. They found that babies born between April and July were more likely to have this defect, establishing strong evidence that seasonality and environmental factors play a significant role in causation.
Read more about this topic: Hypoplastic Left Heart Syndrome