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Archiver > GENEALOGY-DNA > 2004-03 > 1078156460


From: David Faux <>
Subject: Re: [DNA] Smoking - Related STR Mutation
Date: Mon, 1 Mar 2004 07:54:35 -0800 (PST)
In-Reply-To: <f5.382d106e.2d748fb4@aol.com>


Two points Ann, since this "might" be a matter of some potential concern if we are trying to estimate mutation rates.

First you are going to find lots of references to th mutagenic and carcinogenic properties of wood smoke if the wood source is a house or construction site in that the wood preservatives used, creosote and copper sulphate both are potential agents in the smoke that would give it these properties. However, we are speaking about the wood smoke inhaled by generations of our ancestors - coming from everything from oak to peat.

Secondly, I would not be so quick in dismissing the "conclusion" of Holtkempher et al. This was a peer reviewed paper in a respected journal and it is unlikely that the various reviewers would have allowed that comment if they did not see it as having merit in relation to the text. But the reality is that we do not know what factors might potentially trigger a mutational event in the microsatellites of a Y chromosome. For example, what might trigger "replication slippage" ..................... why should we assume that an error is simply a chance event?

This all gets back to my point that it is not warranted to use mutation estimates of .002 or whatever that have been derived from studies of 5000 father - son pairs, or thousands of individual sperm in 3 men since none of these studies even report the haplogroup of the participants (yet this may be a key factor in prediciting mutational rate) let alone assessing lifestyle factors which could be highly significant. My point has always been that none of the estimates apply in anything more than the most general way to an individual family, and like the Most Recent Common Ancestor concept, are not directly applicable to genetic genealogy. Sorry if I seem to repeating myself here - but there is more than a remote possibility that I might be right.

David.

wrote:

Actually, a Google search will bring up large numbers of references about the
chemicals in wood smoke. I used this search strategy:

"wood smoke" mutagenic

More to the point here, though -- I tried and failed to find references about
ANY mutagenic agents and STR mutations. STRs are also called microsatellites,
BTW, so I used that term in my search strategy.

Mutagenic agents (that is, agents GENerating mutations) typically damage DNA,
while STR mutations are simply "mistakes" due to replication slippage. If
you'd like to read more about mutations, there's a whole chapter in one of the
online textbooks at PubMed. There's a lot of unnecessary detail about the
biochemistry, but I noted that the discussion of replication slippage appears in the
section on "spontaneous mutations," not the section on "induced mutations."

This URL ends in .2702 in case it is split by RootsWeb. If you follow the
link to Figure 16-4, there's a rather cool Quicktime animation of replication
slippage.

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&;
rid=iga.chapter.2702

Now of course, the fact that I failed to find a discussion of mutagenic
agents and STR mutations might spur some of you to further research, so have at it!
But if you didn't see my message about the chi-square test on the Holtkemper
data, I must repeat that his study is a very flimsy basis for making
generalizations about smoking and STR mutations. Two smokers, one non-smoker, and a p
value of .2 -- that's just an aside in the article, not a conclusion.



Dr. David K. Faux, P.O. Box 192, Seal Beach, CA, 90740, USA



www.davidkfaux.org


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