2010 National DNA Day Online Chatroom Transcript
This is just one question from an archive of the National DNA Day Moderated Chat held in April 2010. The NHGRI Director and many genomics experts from across NHGRI took questions from students, teachers and the general public on topics ranging from basic genomic research, to the genetic basis of disease, to ethical questions about genetic privacy.
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If a person with Down's syndrome had a child, would the child have Down's also?
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Donna Krasnewich, M.D., Ph.D.:
I am knowledgeable in diseases resulting from abnormal metabolism of carbohydrates.
We know that individuals that with Down syndrome have 3 copies of chromosome 21. It is more complicated than that, however. There are some people with the appearance of Down syndrome who have 3 complete copies of chromosome 21, some have only 2 copies and a fraction of a third copy. Theoretically, it is possible that an individual with Down syndrome may produce an egg or sperm with 2 copies of chromosome 21 instead of 1 copy. This egg or sperm may lead the offspring to have 2 copies of chromosome 21, thus Down syndrome. Our experience, however, is that there are very, very few cases of individuals with Down syndrome having offspring with Down syndrome. Whether this is because the individuals have social barriers, limited fertility or other factors is not entirely clear. |
| Stevenson Middle School in AL (7th grade student) |
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