I suddenly realized that I could find the people who match my late husband Steven M Cooper on his mutated section of the BRCA2 gene at the various DNA testing sites that show chromosome information. His particular BRCA2 mutation, implicated in breast cancer and melanoma, likely contributed to the fatal outcome of his prostate cancer. A problem with doing this is that none of his tested family members match that gene, so there would be no way to know if his matches had his bad maternal BRCA2 or his good paternal one.
Amalie LILIEN Tieger
So should I contact those many people and warn them? I had previously alerted his known LILIEN side cousins to this issue and already a second cousin once removed on his LILIEN line discovered her breast cancer early due to my warning. However I may be sending a false alarm to many. I decided it was something I should do. My family history investigations left me confident that Steve’s mutation came from one of the the parents of his grandmother Amalie LILIEN Tieger (jewish) born in Kalusz, Ukraine. Of course, it may well have originated further back.
First I had to locate the mutation in a numbering system that would translate to what we get from our DNA testing companies. From various google searches I learned that BRCA2 is located on chromosone 13. Looking at the report from Color Genomics, the test his oncologist ordered, I could see the location was a deletion at base pairs 32,913,602_32,913,605. More googling found that this is not the common Jewish BRCA2 mutation. That explains why his initial 23andme test years ago did not find it. Next I found the actual National Health Institute fact sheet for his mutation (click here) which had a click point to the diagram below. Click here for the cancer.gov discussion of BRCA2
Image and details of the problem mutation from the NIH web site
Now to find the people who match him on that segment. I downloaded the full list of his matches with segment information from each site. The easiest site to use was GEDmatch because I could use the segment search function to get just the matches to his BRCA2 section of chromsome 13. At the other sites I had to get the full list of all matching segments and then sort by chromosome and start point to find the matching people.
It is time to update my recommendations on dealing with Ashkenazi Jewish DNA, the DNA of those who are Jewish of Northern European origin, often abbreviated AJ. The usual goals of DNA testing are to find out where your ancestors were from, to find cousins who might have good family stories, to confirm your paper genealogy, and perhaps to check on health issues. There are some special considerations for AJ DNA.
First, for Ashkenzi Jews, the ethnicity results are usually not very useful as they look like this:
Typical Ashkenazi Jewish DNA Origins as shown at Ancestry.com
Of course for some with a larger than 2% non-Jewish percentage, it can confirm a non-Jewish ancestor.
Another deep ancestry goal for the Jewish male is to confirm or look for Cohanim or Levite roots. If your Y haplogroup belongs to one of those (see below) then best to do full Y testing over at Family Tree DNA which has projects for Levites and various Cohen groups. 23andme gives you your high level haplogroup but the other testing companies do not. If you tested elsewhere, click here and scroll end of this article to learn how to get your Y haplogroup: Why Y?.
Slide on Jewish Y Haplogroups – image from a Y haplogroup crative commons image at wikipedia, no longer available
Finding relatives is difficult because all of us Ashkenazim are related multiple times, both way back when and more recently. Most AJs look like 4th or 5th cousins to each other even when that is not the case. Cousin marriages, uncle-niece marriages, and other close family marriages abound in our trees. In my own family, on my Jewish line, my great grandmother fixed up her sister with her husband’s brother to get that dowry for the family business so I have double third cousins. Click here for my article from back in 2014 that suggested that we are all descended from 350 people in the 1300s.
This means the Shared Matches feature at Ancestry is useless to us because it does not show how the two matches are related to each other and that can be quite distant. Both MyHeritage and 23andme are kind enough to show how the shared matches are related to each other.