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Charlottesville, VA
A 25-year-old male asked:

Why does chromosome 13 get an extra copy?

2 doctor answers3 doctors weighed in
Dr. Mark Diamond
Pediatrics 47 years experience
Noone knows: If you mean the birth defect of trisomy 13, noone really knows why that defect is able to survive until birth.Mccoy out!
Dr. James Ferguson
Pediatrics 47 years experience
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.

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Last updated Dec 9, 2013

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