Daniel Neeson/Instagram Daniel Neeson, the son of Liam Neeson and the late Natasha Richardson, is opening up about undergoing surgery for a rare congenital heart defect. "I was born with BAV (Bicuspid Aortic Valve) a condition where the aortic valve has two leaflets instead of the normal three," Daniel, 29, wrote in an Instagram post on Tuesday, March 3. "About 2% of the human population has it, and most people don't even know. It can stay dormant for years before it begins causing valve failure or enlargement of the aorta.