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What Is Chromosome 21
Error in formation: During formation of the egg , the chromosome (c) pairs that make up the normal cell separate and each egg is supposed to have 1/2 of a pair. If a 13 pair does not separate, three rather than a pair of 13's will form when the egg & sperm join. Having an extra 13 in every cell of the fetus confuses the fetal development. Miscarriage or birth defects often occur. ...Read moreSee 1 more doctor answer
Down Syndrome: Trisomies (3 instead of 2 of a certain chromosome) are most common. Down is caused by an extra copy of chromosome 21. Patients usually have lower iq, shortened lifespans and specific facial and anatomic features. Edwards syndrome involves an extra copy of 18. The most common in utero is 16, though spontaneous miscarriage rates are very high. Patau syndrome (extra 13) also has a high mortality. ...Read moreSee 1 more doctor answer
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