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From:
Subject: Re: [DNA] Haplotype Q and Autosomes
Date: Sat, 12 Nov 2005 10:48:18 EST


In a message dated 11/11/05 8:29:20 PM Pacific Standard Time,
writes:

> Thanks David, David, Doug and others for the helpful information. I
> realized
> after I sent my post that mtDNA should have been xDNA (is that the way to
> write it?). I knew mtDNA is passed through the female and so tripped on it.

In your first message, you wrote "I would assume that the shape of my teeth
would be determined by autosomes and not by the yDNA markers for Haplotype Q
and that these autosomes could come from either mtDNA or yDNA. Or both."

Actually, the X chromosome is not an autosome, either. Autosomes are the 22
chromosomes that *always* come in pairs (numbered 1 to 22, roughly in order of
decreasing size), and X and Y are called the sex chromosomes. That's a bit
confusing, too, since it's a gene on the Y chromosome that is responsible for
determining gender. The Y has very few genes at all (27 by one way of counting),
mostly concerned with sperm production. The X chromosome has over a thousand
genes, most of them not concerned with sex-specific traits. The "complete"
sequencing and annotation of the X was just announced earlier this year:

http://www.sanger.ac.uk/Info/Press/2005/050316.shtml

Since SMGF includes X STRs in their research program, and since Thomas Krahn
has already made some tests available, I think it's important for everyone to
understand how the X is inherited. There are diagrams in my book "Trace Your
Roots with DNA" on page 27. You can use the "Search Inside the Book" feature at
Amazon (no charge, but you must have a credit card on file) and use "weasel
word" as the search term.

http://www.amazon.com/exec/obidos/ASIN/1594860068/

Now I've gone far astray from your original query! I typed in incisors at
OMIM (Online Mendelian Inheritance in Man), since I knew that shovel-shaped
incisors are associated with Native American ancestry. It does not appear that this
trait has been located to any chromosome.

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=147400

As a matter of fact, if you type in "teeth" as a search term, there are very
few dental traits where the gene has been identified. (If a gene has been
identified, a listing would show something like 4q21.3, meaning that it has been
narrowed down to a region on chromosome #4.)

Ann Turner


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