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View Full Version : Behavior of extra copies of mutli-copy markers (464)



RobertCasey
11-24-2017, 04:40 PM
I am one of the admins of L226 and we have an exciting development discovering a much older branch just above L226 - FGC5618. Only one person has been confirmed to be FGC5618 POS and L226 NEG, so FGC5618 is currently a very small scope branch. L226 has a very genetically isolated signature of nine mutations and this new tester shares only five of these mutations - FGC5618 is obviously a much older branch since it is missing half of the signature of L226. The FGC5618 tester also has fifteen mutations from the L21 modal as well. L226 is around 1,500 years old when it became prolific and has around 30 L226 equivalents which make the actual L226 mutation much older than that. The FGC5618 tester just ordered a Big Y, so it will be some time before we know how he tests for these L226 equivalents (to date, he has tested positive for five of the L226 equivalents that have been tested).

Unfortunately, this tester has three multi-copy markers with extra markers. He has three values for 459 (9-10-10) and CDY (36-37-37). The tough one is that he has six markers of 464 which includes three of the nine mutations of the L226 signature. This is main challenge with his 464 values of 13-13-15-15-16-18. For 459, the L21 modal is 9-10 and L226 modal is 8-9, so I suspect that the 5618 tester went from 9-10 to 9-10-10 probably prior to the L226 mutation to 8-9. I do not use CDY markers for charting due to the fact that 40 % of all 67 marker mutations are CDY - too fast for reliable charting.

I am attempting to understand the evolution of the 464 markers. The L21 modal values for 464 are 15-15-17-17 and the L226 modal values are 13-13-15-17. The FGC5618 tester is 13-13-15-15-16-18. I am attempting to figure out how these marker values mutated and determine if these extra copies played a role in the L226 signature by possibly being a direct ancestor of L226. With this assumption (which may not be true as these extra markers may be unique to just his path and share no common ancestor with L226). Here are a couple possible YSTR progression scenarios:

L21 - 15-15-17-17
Pre-FGC5618 - 13-13-15-17

Then two branches
FGC5618 - 13-13-15-15-16-18 (do the unique value of 13s pre-date the extra copies and does 15 predate the extra-copies)
L226 - remains 13-13-15-17

OR

L21 - 15-15-17-17
Pre-FGC5618 - 13-13-15-15-16-18

Then two branches

FG5618 - remains 13-13-15-15-16-18
L226 - 13-13-15-17 (when the markers reverted back to four copies)

I plan on looking for signature matches the FGC5618 tester to see if other match his very large 15 mutation signature as well. But for now I am attempting to understand how the extra copies come and go. The Big Y test that is pending for the FGC5618 tester will test most of the L226 equivalents (not all since we have several that FGC YElite discovered and not included in Big Y coverage). FGC5618 will probably move most of the L226 equivalents to FGC5618 equivalents. However, I do not see how this is going to change the analysis of the progression of the YSTR markers.

Are there is academic papers on how 464 markers add and lose these extra marker values ? This is one issue that Big Y is not really going to help but building the YSTR cluster for FGC5618 could shed light on how these markers evolved.