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Archiver > GENEALOGY-DNA > 2007-07 > 1184470515


From: Gabriela Novak <>
Subject: Re: [DNA] Do Haplogroups change after death?
Date: Sat, 14 Jul 2007 23:35:15 -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><10D7B287-14E3-4822-829C-FC5EEFE2A3A7@vizachero.com>
In-Reply-To: <10D7B287-14E3-4822-829C-FC5EEFE2A3A7@vizachero.com>


Please also keep in mind that even during degradation, the changes
are random, different changes will occur in different cells, so the
overall effect you will get during sequencing is a smear, if
anything. Not a specific change. The DNA basically breaks into
pieces, there is no "repair" to change the sequence. Not to mention
getting the same sequence change in every cell to the same altered
sequence. That will just not happen.

Gabriela


On 14-Jul-07, at 11:14 PM, Vincent Vizachero wrote:

>
> 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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