This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Paediatrics, Subject name: Pediatrics
The child shown below is suffering from a congenital hea disease. Which congenital hea defect is seen most commonly seen in these children? 
Select and explain. 
A. Patent ductus aeriosus, B. Atrial septal defect, C. Atrioventricular septal defect, D. Ventricular septal defect
C: Atrioventricular septal defect
Answer: C: Atrioventricular septal defect 
Explanation: This child is suffering from Down syndrome. Impoant 'must know' facts about Down syndrome: - Trisomy 21 - MC - d/t maternal meiotic non-dysjunction - Risk increase with increase in mother's age - QMc hea disease in Down syndrome - AVSD (Atrioventricular septal defect) aka Endocardial cushion defect