Most common preventable cause of mental retardation:-: (A) Down's syndrome, (B) Congenital hypothyroidism, (C) Rett's syndrome, (D) Fragile x syndrome
Answer is B. - Congenital hypothyroidism is the M.C preventable cause of mental retardation - In India incidence is 1:1000 - Most common cause of congenital hypothyroidism is thyroid dysgenesis. - Most common cause of congenital hypothyroidism with goitre- Thyroid dyshormonogenesis.