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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Down syndrome most commonly occurs due to ____
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The correct answer is  Down&;s syndrome occurs due to nondisjunction in maternal meiosis. Down&;s syndrome: Most common chromosomal disorder Incidence: 1/800 live bihs Mechanism: Trisomy 21 (meiotic maternal nondisjunction) (95%) Robesonian translocation: 4% Mosaic pattern: 1% Non-disjunction points to the failure of the homologous chromosome to seperate during the meiotic division. Ref: Nelson textbook of pediatrics 21st edition Pgno: 658