I did some visual phasing for Jane and her two siblings. Now Jane wants to see how the visual phasing can be used.
Mr Gray’s 8.5 cM Match
Jane’s first question came from a Mr Gray. He matched Jane and her two siblings at about 8.5 cM. Jane had this conundrum:
For me the match points to Beckham, for Heather it points to Beckham but for Alex it points to Hamilton. Unless it is on Mum’s side as indicated by Jackson for all three of us, but then why wouldn’t Mum share DNA with Mr. Gray?
Here is the right side of Jane’s Chromosome 2 Map. Jane is in the middle bar and her maternal side is on the top bar.
Here is where Jane matches Mr. Gray:
The answer for this one is that this is not a real match. Jane’s mother has tested and Jane has two sets of phased results based on her mother’s results. I ran Mr. Gray against Jane’s paternal and maternal kit and got no results. This means that the match is not real. Different analyses have been done for the chances of a certain size match being real or not. Here is one from Roberta Estes:
These studies seem to show that there is about a 50% chance of a 7 cM match being real. This goes up to a 66% chance of being real for an 8.5 cM match. It looks like Mr Gray fell into that 34% range. The only other possibility is that Jane’s mother could have had a false negative match with Mr. Gray. All in all, I would say that these results would be inconclusive. For me, I tend to say if there is no match on the two phased kits, then there is no match.
Second Example: An Adoptee at 23andme
Only Jane and her mom tested at 23andme. Here is how the adoptee matched Jane:
Chromosome 1: 108 to 151 26 cM
Chromosome 2: 225 to 230 8 cM
Chromosome 3: 104 to 145 41 cM
Chromosome 17 5.7 to 9.3 9 cM
By looking at the Visual Phasing Spreadsheet, Jane deduced that this was on her Beckham Line:
Jane is in the middle bar. The bottom of that bar is her paternal side where Bekham is in blue. I assume that Jane’s mother did not match this adoptee at 23andme.
I have Jane’s Chromosome 2 above where she matches Beckham between 225 and 230 on her paternal side.
The match is significant for Jane as the match between 104 and 155 goes through her maternal crossover at position 110M. That would confirm that this is a paternal side match on Beckham.
Here is Chromosome 17:
It looks like I had trouble identifying the maternal grandparents, but Jane matches this adoptee in her paternal Beckham region. So I would agree with Jane that this match is on her Beckham side. It would help if this adoptee uploads his/her DNA results to gedmatch.com.
Peggy’s Maternal Match on Chromosome 13
Jane reports these results for Peggy’s matches to her and her siblings:
Heather 74 to 103 31.5 cM
Jane 74 to 91 14 cM
Alex – no DNA
Without looking at Jane’s map, it appears that Jane should have a maternal crossover at around 91M.
Jane has a maternal crossover at 90 on the map where her DNA goes from Adair to Jackson. Alex is on the top row. He has a large maternal Jackson segment which explains why he has no match with Peggy. Jane has determined correctly that this match is along the line of her maternal Adair grandmother.
A Paternal Hillock Match on Chromosome 2
This match has a similar pattern to the previous one. Here Hillock matches:
Jane 40 to 79 41 cM
Alex 119 to 208 8.4 cM
Heather – no DNA
Two siblings match Hillock and one does not. However, in this case, the two siblings match at different locations on Chromosome 2.
Jane again is shown on the middle bar. The paternal side is on the bottom where she matches on her Hamilton grandfather. The match with Alex on the top shows that he should be matching on the Beckham paternal grandmother. However, this is a small match. It is time to check Alex’ paternal phased kit against Hillock.
I forgot that I had lowered the threshold and was surprised to come up with this result:
The location of this match is within the orange Hamilton segment for Alex’ top bar. The match that Jane reported for Alex should have been 199-208 (unphased). That means that my red circle above on Alex’ bar above is not correct.
Summary and Conclusions
- Jane is fortunate to have a mother whose DNA could be tested. This gives her paternal and maternal matches for Jane and her two siblings.
- It is important to know first whether the match is on the maternal or paternal side.
- If there is no maternal or paternal match, I consider that to not be a match.
- Jane’s conclusions appear to be correct as far as on which grandparent line her matches are on. However, it is important to make sure that the position numbers of the matches are correct to match up with the right grandparent.