Expert: Florence M Rollwagen - 3/29/2009

Question
would the diagnosis of turners syndrome in a single cell zygote necessarily mean that every cell of the body contains 45 chromosomes? can you please explain this? thanks

Answer
Hi Danial:  Thanks for your question.  In Turner's syndrome (45, XO) an error in gametogenesis results in a sperm or egg missing an X chromosome.  The resulting fetus has only one X chromosome, and the normal complement of autosomes.

It results in a female child with various growth abnormalities, such as short stature and neck webbing.  The child also cannot undergo puberty since normal ovaries are not present.  Ovaries need two X chromosomes to develop.

In females, one X chromosome undergoes inactivation and can be seen as the Barr body in female somatic cells.  In ovaries, however, the second X is not inactivated and goes on to form normal ovaries and eggs in utero.

So in fact, females with Turner's syndrome do have only 45 chromosomes in each cell.

Here are some links:
http://en.wikipedia.org/wiki/Turner_syndrome
http://www.nlm.nih.gov/medlineplus/turnersyndrome.html

Hope this helps, write back if you have more questions.

FM Rollwagen, PhD