A patient with trisomy 18 presents with overlapping fingers, rocker-bottom feet, and cardiac abnormalities. What meiotic error most commonly causes this condition?
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Correct answer: Maternal meiosis I nondisjunction
Trisomy 18 (Edwards syndrome) is most often caused by maternal meiosis I nondisjunction. Advanced maternal age is a major risk factor. Postzygotic errors more commonly cause mosaicism.
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