Sunday, August 20, 2017

BIG Y: I got it, I don't got it?


The Big Y DNA test is an advanced Y DNA test, of course for males only. The test is designed to place testers on the Y haplogroup tree. A haplogroup tree looks something like our pedigree chart. There are off shooting branches from our ancient common lines leading down to more modern times.  haplogroups generally only tell us about our ancient geographic roots, and migrations. The BigY is attempting to change that by identifying more modern haplogroups, using novel variants, making it useful for genealogy.

Our Current Position on the Family Tree DNA Haplogroup SNP Tree

My Forgey family is now in the Big Y at Family Tree DNA (FTDNA). My uncle and one of his 5th cousins, once removed, have been upgraded to the Big Y. SNP's or mutations, Single Nucleotide Polymorphicisms, are determined by the mutations of nucleobases ATCG which are used to determine someones haplogroup. A Nucleobase base at one particular position, which differs from a reference sample determines whether a tester is positive for a particular SNP or mutation.

My Uncle and his 5th cousin once removed both shared the same nucleobase for a SNP that had not yet been named as a haplogroup. When a SNP hasn't been named yet it is identified by a long string of numbers giving its position, such as 2580707, the reference may be A for that position, but the tester may be G at that position, meaning there was a mutation (which my uncle and cousin matched exactly in their case in order to be a match and test positive for the newly named haplogroup). If two or more people match at that position with the same base (ATCG) this SNP may, or may not, be deemed significant enough to be named as a new haplogroup.

Some of the SNP's now being identified by name as haplogroups may be fairly recent? It does appear, as these haplogroups are added, they are mainly shared by specific surnames, or since surname groups are over represented they may just represent the geographical area where these surnames developed?

My uncle and his 5th cousin, once removed, now have their own haplogroup which no other tester so far shares. Before this haplogroup SNP was discovered,  likely by the I-M223 group administrator Wayne Rogers at FTDNA, we were in the haplogroup I-BY3819 that was estimated to be 900 or more years old making it useless for genealogy purposes. It did confirm our Scottish origins however, plus suggest the name is derived from Ferguson the dominate surname in that haplogroup.  The new haplogroup could be either unique to our surname, or the geographical area our family lived in, or even more widespread? Hard to say since so few men have tested.

A way to test how old this haplogroup might be would be to SNP test for the new haplogroup BY19896/BY198967. We know both of our Forgey Big Y testers share a common ancestor around 300 years ago. We don't know when the other Forgeys who settled in America share a common ancestor? It would be interesting to see if all of the Forgey lines share the same terminal SNP. It costs $39 dollars to test a SNP. Much cheaper than the Big Y. So this kind of testing is doable.

Something I don't get is YFull has quality scores for SNP's which seem to disagree with conclusions about SNP's made by Big Y? Hence  "I got this, I don't got this" in my title for this post. The yet to be named SNP's are called Novel SNP's. YFull also calls those SNP's only found in a single tester private. When more than one tester shares a SNP it isn't private anymore, and becomes unlocked which can lead to breakthroughs. So it is good to test as many distant cousins at different degrees of relationship, or those sharing the same surname as you can afford to unlock these SNP's, which hopefully we lead us to more modern times.

According to FTDNA both of our testers have around half a dozen high confidence positive results on yet to be named SNP's. YFull has a propriety SNP quality rating system. My uncle's test is still being analyzed by YFull so we don't know the quality of his yet to be named, or novel SNP's? Roger's analysis has been completed and according to YFull the best quality of novel SNP's he has are two in the "acceptable category". None what they call "best quality". The rest are rated my by them as  "ambiguous".  The SNP's shared between my uncle, and his 5th cousin once removed,  are all classified as ambiguous by YFull? Not sure of the quality rating for these SNP's will affect our placement in the YFull tree? Will YFull recognize the I-BY19896 haplogroup? Or keep us in the I-BY3819 haplogroup?

My uncle and his 5th cousin, once removed, each share many novel SNP's, but also have a couple they don't share, which may prove helpful if these SNP's are ever added for SNP testing. They would appear to have developed later than 300 years ago? Some novel variant SNP's may be significant and some may not? We also have unnamed novel SNP's shared by many others, likely quite old. We just have to wait and see where this all leads. I'm still learning how to work with these results, and rely on expertise of the group administrators like Colin Ferguson and Wayne Rogers.

You can learn more about the Big Y by watching these Youtube videos:

Here you can see novel SNP's represented by the numbered positions far left. These are the results for our two Forgey testers as you can see they share most of the same novel SNP's but not all. These mutations are probably more recent than 300 years.