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Archiver > GENEALOGY-DNA > 2006-01 > 1136434093


From: "John E. Mellick" <>
Subject: Do Living Men Mutate? (was Y-STR Mutation rate)
Date: Wed, 04 Jan 2006 23:08:13 -0500
In-Reply-To: <200601050033.k050X1kE024910@lists5.rootsweb.com>


John,
Thanks for the explanation. Looks like I'm a little out of my element
here. But aren't cells continually dying and being replaced. I think I
had wondered if the replacement cells could be different from the earlier
cells, and then what kept all the many cells in the body alike?

Maybe I should go back and play with my Altair, that had a quarter k static
ram. That chip was about 1 1/2 x 4 inches. Never could get it to play
pong, tho.

JohmM
(Germany c1500, to America in 1728 >PA>NJ>IL>IA>KS>OK>FL)

John Chandler wrote:
>Date: Wed, 4 Jan 2006 16:40:31 -0500 (EST)
>From: (John Chandler)
>To:
>Message-Id: <>
>Subject: Re: [DNA] Y-STR Mutation rate
>
>JohnM wrote:
> > Now, I've put all this down to ask a question. ARE A MAN'S MUTATIONS
> FIXED
> > AT BIRTH, OR DO THEY INCREASE AS HE AGES?
>
>If you mean the Y DNA mutations detected by commercial tests, they are
>fixed at birth. These tests sample a large number of cells and therefore
>would not detect a stray mutation that occurred after birth. Mutations
>do occur, though, and a mutation in a germ-line cell can be passed on
>to the next generation.
>
> > with increased risk for cancer. Also, the DNA has been found to mutate
> > rapidly for example in response to cancer. " I read this statement to say
> > that dna mutates when attacked by cancer. Is this true? Can a man have
> > some cells in his body with different mutations than other cells?
>
>You have to be careful here. Substances that cause mutations can also
>cause cancer and vice versa.
>
> > This statement indicates to me that ydna mutates more rapidly as the man
> > ages. Is this correct?
>
>No, but once a cell has mutated, it can't unmutate, except by
>recombination, which is itself a mutation, and doesn't restore the
>status quo ante in a heterozygous individual. Thus, the number of
>cells with mutations tends to increase over a lifetime. Of course,
>young people may be protected from harmful substances and thus have
>a slower rate of mutation than adults, but there's no getting away
>from cosmic rays and other background radiation.
>
> John Chandler



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