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Archiver > GENEALOGY-DNA > 2007-07 > 1184469296


From: Vincent Vizachero <>
Subject: Re: [DNA] Do Haplogroups change after death?
Date: Sat, 14 Jul 2007 23:14:56 -0400
References: <008701c7b415$794b0120$2401a8c0@your447023ae6b><REME20070705181857@alum.mit.edu><a81622ac0707051724y16754956obfb853b6686e74ed@mail.gmail.com><REME20070707152459@alum.mit.edu><a81622ac0707071304x11373a0en3b0b4e52a7b2e3c@mail.gmail.com><REME20070707183721@alum.mit.edu><a81622ac0707071637o34a3421dr36660529da9f75a4@mail.gmail.com><REME20070709202718@alum.mit.edu><a81622ac0707092003u290a5dd4s96c4a87a62fe3230@mail.gmail.com><REME20070711175004@alum.mit.edu><a81622ac0707120434g62d3796bk63d9ce33299bb67c@mail.gmail.com><REME20070713160416@alum.mit.edu><7.0.1.0.2.20070715011550.02457910@netvision.net.il>
In-Reply-To: <7.0.1.0.2.20070715011550.02457910@netvision.net.il>


On Jul 14, 2007, at 6:18 PM, yair wrote:
>
> Haplotypes are determined by STRs which are considered relatively
> volatile whereas haplogroups are determined by SNPs which are
> considered stable.

It would be more precise to say that STR haplotypes occasionally
undergo small changes as they pass from one generation to the next,
whereas haplogroups do not.

> It is admitted that haplogroups may change from one classification to
> another AFTER DEATH due to what is termed "Degrading" or
> "deterioration".

It would be better to say that DNA degrades after death, so that it
is sometimes difficult or impossible to accurately determine an
organism's STR haplotype or its haplogroup from an examination of its
remains.

> The explanation is that while the organism lives a defence mechanism
> maintains that haplogroup as it is.

I would say that organisms can repair their own DNA. It really isn't
a "defense" mechanism per se, since their is no attack, and
maintaining the haplogroup is just an incidental effect at best.

http://en.wikipedia.org/wiki/DNA_repair

Of course, after death that repair mechanism will not function.

> After death the defence mechanism is removed and changes can take
> place.
> it would therefore appear that SNPs are not necessarily as stable as
> all that and hypothetically at least external influences could
> conceivably have the same effect on a living organism.

It would not be reasonable to infer that degradation of DNA after
death offers any insight into its behavior during life. We already
know that mutagens exist anyway, but it is extraordinarily unlikely
they would act in such a way that the SNPs used to establish
haplogroup would be noticeably affected.

Vince

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