This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
All are common in Down syndrome, except ? 
Select and explain. 
A. Simian crease, B. Clinodactyly, C. Mother's age > 35 years, D. Respiratory tract infection uncommon
D: Respiratory tract infection uncommon
Answer: D: Respiratory tract infection uncommon 
Explanation: Ans. is 'd' i.e., Respiratory tract infection uncommon Chronic rhinits, conjunctivitis and periodontal disease are common in Down's syndrome. Lower respiratory tract infections pose a threat to life. Pneumonias are common in patients with Down's syndrome.