Archiver > GENEALOGY-DNA > 2005-03 > 1110334444

Subject: Y-linked diseases [was Re: [DNA] DNA Direct]
Date: Tue, 8 Mar 2005 21:14:04 EST

In a message dated 03/08/05 11:24:03 AM Pacific Standard Time,

> My comment about disease was that mastocytosis, is a rare disease passing
> from father to children. Only to be passed on through the male genes. Has
> anyone on the list encountered this rare disease doing there DNA research.
> If so contact me. I would be interested in learning more. Also I am trying
> to find out how far back this disease can be traced back. Using my DNA
> research. Being a newbie to this list and DNA subject matter. But I am
> learning. Please be patient.

Jeff, I checked mastocytosis at OMIM (Online Mendelian Inheritance in Man)

It does not list any Y-linked genes, although there is an X-linked gene. Some
traits and diseases on the X chromosome only show up in men, because they
only have one X chromosome. Women have two X chromosomes, and a defect on one X
chromosome can be compensated for by the normal X chromosome.

What we call "classical genetics" has not come up with any Y-linked traits or
diseases. Classical genetics studies how a trait has been passed down in
family pedigrees. Now that the complete (more-or-less) sequence of the Y
chromosome is available, we may learn about a few traits, but for the most part, the
very small number of genes on the Y chromosome are concerned with sex
determination and sperm production. If the Y chromosome had a unique gene that was
essential to life, women would be at a severe disadvantage!

There has been some discussion about whether Y chromosome testing can reveal
fertility problems. Some fertility problems are correlated with a whole-scale
deletion of a large segment of the chromosome, which includes DYS464. In such
a situation, DYS464 doesn't show up at all. It's apparently very uncommon, but
we did have a report of one case on this list. There will be a article on
this in the April Journal of Medical Genetics, and we'll return to that topic
when it comes out.

In the meantime, I haven't mentioned this book in a while: "The X in Sex" by
David Bainbridge. It has a lot of interesting background about the X
chromosome and some sidelights on the Y as well.

Ann Turner - GENEALOGY-DNA List Administrator
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