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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what happens if you have more than 23 oairs of chromosomes?
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Emily Edelman, M.S., C.G.C.:
I am a genetic counselor who coordinates multiple projects at a non-profit organization dedicated to providing education in genetics to healthcare providers. I currently work with other genetic counselors, scientists, physicians, nurses, physician assistants, bioethicists, patient advocates, and other health professionals. I also have experience in providing genetic counseling to individuals with a family history of cancer, and other rare and common conditions.
Great question. Having more or less than 23 pairs, or 46 total, chromosomes, is called aneuploidy. The effect of aneuploidy depends on the specific chromosomes involved. In general, the bigger the chromosome, the more serious the effect. Many forms of aneuploidy are so serious that these fetuses die very early on in pregnancy. Other forms of aneuploidy result in different physical and mental characteristics. The most common form of aneuploidy that we see is Down syndrome. Down syndrome is also known as Trisomy 21, where there are 3 copies of chromosome 21 rather than the normal 2. The most mild forms of aneuploidy are those conditions that affect the X and Y chromosome. Sometimes these people do not even know they have an extra or missing X or Y chromosome! |
| McClesky Middle School in GA (7th grade student) |
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