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Name: Amanda W.
Status: Student
Age: 18
Location: N/A
Country: N/A
Date: N/A 

My class is debating the issue of genetically engineering an embryo to make it a certain sex, in this case male. In defense of altering the embryos current sex, the defendant is the claim the father possesses no y-chromosome to give therefore he will forever produce female offspring. So, my question is: Is there any possible way that current or near future technology could produce a male offspring from such a father or an xx set of chromosomes without the use of artificial insemenation?

Reply: The gene which switches default female, development to male resides on the Y chromosome and is known as SRY. There may be a few other genes associated with maleness on the Y chromosome, but most literature refers to SRY as the key in determining a male. There are documented medical cases where an individual with the genotype XX was phenotypically a male. In these cases, the SRY gene had undergone translocation, presumably during crossing-over, and was improperly carried on the paternal X chromosome. Thus fathers' whose sperm carried the altered X parented male children. Obviously, this is not an ideal solution, as it is yet to be discovered what other "essential" gene may be lacking due to the loss of the entire Y chromosome. Additionally, the reliability of producing boys in subsequent generations is not established.

However, to answer your question of producing boys without artificial insemenation, it would not be possible unless the father was naturally producing an abundance of altered X sperm. With artificial insemenation, it would be possible to use the father's sperm and alter it so that all or most X chromosomes did carry the SRY gene. Also it would be possible to take an XX zygote and infuse it with the SRY gene, although the ethics would pose a serious barrier. The failure rate for the uptake in a zygote for any specific gene is still very high. It is much too high to be acceptable for a human where the results could be disastrous mutation or death for a viable fetus.


I suppose so...The Y chomosome is quite small and along with the SRY gene does determine maleness but mostly very early in gestation. It would be possible to extrachomosomally engineer such proteins to come into play at the proper times to remain female...remember we all begin as females and then in the first trimester the sry gene turns on for just a short while beginning the course towards maleness.

Peter Faletra Ph.D.
Office of Science
Department of Energy

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