Which is MC genetic cause of mental retardation -: (A) Tuberous sclerosis, (B) Cri-du-chat syndrome, (C) Fragile-x-syndrome, (D) Angel's syndrome
Answer is C. Ans. is 'c' i.e., Fragile-X-syndromeo Down's syndrome is the most common genetic cause of mental retardation, and fragile-X is second to Down's.Also know o Most common inherited cause of mental retardation is fragile-X-syndrome (because down's syndrome is congenital cause but not inherited).