As stated before, the gene for hemophilia is an example of a sex linked gene. It is only found on the X chromosome. It is very very rare in females because it is rare for a female to have a hemophiliac father (he would have to have the defective gene on his X chromosome and would need to live to a reproductive age) and a carrier mother (one who has the defective gene on one of her X's) . This female offspring would have to be very unlucky. There would be a 50/50 chance of her being afflicted. From her father she would inherit the only X chromosome he has, but from her mother she could get either of the X chromosomes ... the one with the "good" gene or the one with the "bad"gene.
Sometimes, more frequently with older women, a chromosome does not split properly and the infant will get an extra chromosome. When this happens it is called a tri-somy. (three chromosomes inherited by the infant instead of the usual two). When this happens with the 21st chromosome the offspring will exhibit Down's Syndrome. Other defects are caused by trisomy conditions with other chromosomes. Pat ========================================================= "Magic Commands": to stop receiving mail for awhile, click here and send the email: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20NOMAIL to start it up gain click here: mailto:[EMAIL PROTECTED]?body=SET%20CKCS-L%20MAIL E-mail [EMAIL PROTECTED] for assistance. Search the Archives... http://apple.ease.lsoft.com/archives/ckcs-l.html All e-mail sent through CKCS-L is Copyright 1999 by its original author.
