GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2010-11 > 1288631854


From: Ann Turner <>
Subject: Re: [DNA] Help with analysis of Family Finder Results
Date: Mon, 1 Nov 2010 10:17:34 -0700
References: <8CD4229D2F50058-1E98-1AF8C@webmail-d012.sysops.aol.com><AANLkTinv2idu9w+161rgta0uvSuDcMhrG-=8VMajYZpV@mail.gmail.com><6.0.1.1.2.20101025130115.04ded578@mail.utexas.edu><AANLkTin5ZR=2CQk5c3YuTVsya+jY1GQc3uDWUO1BgQyp@mail.gmail.com><AANLkTim=6QjNadw0RY80xjJLaKr9d-iof59mSjvb8C4N@mail.gmail.com><AANLkTinwOyQ+j+Krv-oXzPh8kjo1-GfjHf9imp2nnnzD@mail.gmail.com>
In-Reply-To: <AANLkTinwOyQ+j+Krv-oXzPh8kjo1-GfjHf9imp2nnnzD@mail.gmail.com>


According to their FAQ, FTDNA does split blocks that span centromeres as
well as some other SNP poor regions:

http://www.familytreedna.com/faq/answers/default.aspx?faqid=17#609

The splits are due to their method of selecting informative blocks, not a
biological reality. 23andMe handles this by requiring more SNPs and/or cM
for segments that include SNP deserts. For your purposes, I think it would
be OK to concatenate blocks that straddle a SNP desert.

Ann Turner

On Mon, Nov 1, 2010 at 7:40 AM, John S Walden <> wrote:

> List
>
> I have figured out the splitting of blocks issue
>
> FTDNA will "bridge" a block across the centemere but does not bridge it
> across one
> of the SNP poor regions.
> I wonder if there is a "right" way to handle this.
> If there are no SNPs there then the two people match 0 = 0 thus it should
> bridge??
>
> John W
>


This thread: