I had not been able to finish watching the last half hour of the Jamboree Webinar I purchased until last week. For some reason (maybe the fact I use Wifi?) I kept losing the video signal half an hour into it, and could never advance passed that. I purchased the session "TECHNIQUES FOR USE OF AUTOSOMAL DNA TESTS TO BREAK THROUGH GENEALOGICAL BRICK WALLS" (link to syllabus1, syllabus 2).
The techniques used by Dr. Janzen focus on establishing a good foundation for drawing conclusions using shared segments. Having your parents tested allows you to do phasing which is extremely useful. Even if you only have one parent test it's very useful. The more close cousins you test or compare with, such as 1st through 3rd, puts you in a better position when it comes to making connections with more distant cousins. The segments shared at these cousin levels tend to be large, and more conclusive than the much smaller segments shared by distant cousins. You can extend the length of your ancestral segments if your matches shared segment extends beyond yours. When you find others sharing smaller segments at 4th cousin and beyond you can then more confidently label those segments. Unfortunately, 23andme and Family Tree DNA are on different builds, with 23andme on the 37 build and Family Tree DNA is on the 36 build. This just means more positions have been added to the chromosomes by 23andme, making them longer. This can lead to problems when comparing between companies. Family Tree DNA may eventually move to the 37 build or advance to a 38 build.
Dr. Janzen emphasized the need to take great care before assuming you received a segment from a particular ancestor. You need to look for all possible connections going back as far as possible. His example was the surname Broshears (which coincidentally has a connection with my family). This name isn't very common so he assumed that was his connection with one of his matches. Doing more research he discovered it was not their shared ancestral line. Instead it was Alexander.
|Our Mullens lived 15 miles from one|
of my matches Mullens
|Use with caution (from ISSOGG site)|
Someone asked a question at the end directed toward the medical side of testing since Dr. Janzen is a medical doctor. They wanted to know how useful 23andme type testing is. He said it can provide useful information, but isn't really that informative at this time. As he said a majority of illness is due to factors not related to DNA. Lifestyle is the number one contributor to disease and illness.
Dr. Janzen's session points up the need for easy access to segment information. Without it we can't confidently draw conclusions. He stated we need to put pressure on the testing companies to release this information.
(Another aside, I just finished listening to Dr. Janzen speak again about the use of segments. He said he feels testing 2nd cousins offers more bang for your buck).