Dear Ann, I reviewed the list of people in 23andMe whose segments over 7 cMs in length are IBS and I have the raw data files for several of these people: CH and MN, whose IBS segments are exactly 7 cMs. Both are of Low German Mennonite ancestry. I am not in contact with any of the other people whose segments are IBS. Are you interested in doing additional review this situation in some way? Sincerely, Tim Janzen -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ann Turner Sent: Thursday, January 12, 2012 6:52 AM To: [email protected] Subject: Re: [AUTOSOMAL-DNA] SUBJECT: How do you work a 5 way FF match with few clues ? I wonder if your percentages run higher than mine because of compound segments: short segments that butt up against each other to make it look like one continuous segment. This is FTDNA's explanation for this phenomenon, but I haven't yet encountered a real-life case. I can see it would be more likely in an endogamous population like your Mennonite ancestry. Do you have contact information for some of the 7+ cM cases that are IBS? Ann Turner

Yes, I think it would be interesting to compare the phased data of the child with the genotypes of CH and MN. It could be a case of "fuzzy boundaries" (the segment is actually present in the parent, but just misses the threshold by a few SNPs), or it could be composed of a few or many smaller segments. I'd guess the first possibility is unlikely, since your stats are based on Ancestry Finder showing segments down to 5 cM in size. I know you've developed some spreadsheet tools -- would this be a tedious task? I work with David Pike's utilities (which can handle files where the SNP list is not identical), and I can do the analysis. It's not automated for me, either -- it's a combination of manipulating Pike's output with a little BASIC program plus some spreadsheet formula. Ann Turner On Thu, Jan 12, 2012 at 8:30 PM, Tim Janzen <[email protected]> wrote: > Dear Ann, > I reviewed the list of people in 23andMe whose segments over 7 cMs > in length are IBS and I have the raw data files for several of these > people: > CH and MN, whose IBS segments are exactly 7 cMs. Both are of Low German > Mennonite ancestry. I am not in contact with any of the other people whose > segments are IBS. Are you interested in doing additional review this > situation in some way? >