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Archiver > GENEALOGY-DNA > 2012-03 > 1331210278


From: Thomas Roderick <>
Subject: Re: [DNA] DNA matching of cousins
Date: Thu, 8 Mar 2012 07:37:58 -0500
References: <mailman.3465.1331175780.23469.genealogy-dna@rootsweb.com>
In-Reply-To: <mailman.3465.1331175780.23469.genealogy-dna@rootsweb.com>


Ann, this seems more than coincidental. Something could be affecting recombination in your Chromosome 4. "Suppressing" often used, is not the right term. Anything where recombination might lead to gamete or zygote lethality. Could you have an inversion in Chromosome 4? A cross-over within a paracentric inversion leads to an anaphase bridge in Meiosis I, and the bridge would hang on making the products of that recombining meiosis lethal. A crossover within a pericentric inversion could lead to major chromosomal imbalances, also producing lethality. So most of the inverted chromosome could be transmitted intact from generation to generation because the recombinants don't survive. Carriers of inversions are not themselves medically affected because they have a full complement of the chromosome. Have you or your relatives ever had a karyotype done? In your families were there more than the usual number of miscarriages or uterine deaths?
Tom

On Mar 7, 2012, at 10:03 PM, wrote:

>
>
>
> Message: 10
> Date: Wed, 7 Mar 2012 19:02:29 -0800
> From: Ann Turner <>
> Subject: Re: [DNA] DNA matching of cousins
> To: ,
> Message-ID:
> <CAA-Ub_BtBncW-USsq4NrLC6NOdQtckj___XB9OB+>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Alas, I have a counter-example. By some fluke, the entire length of
> chromosome 4 has been passed down in my family to paternal uncle, my sister
> and me (and therefore our father) and virtually all of (196 cM) it to my
> uncle's grandson (my first cousin once removed). This is undoubtedly an
> outlier, but just another sign that it's hard to come up with foolproof
> guidelines once you're past full vs half siblings.
>
> Ann Turner
>



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