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Sinclair DNA - Mutation Rates

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If a family can determine their mutation rate, many things fall into place. For instance, if someone shows up in the project and is a distance of 1 off, and they know the man’s ancestors don’t match in the time frame of the Empire Era of the British Empire, they can surmise this person shares a MRCA just before that period. In the Sinclair DNA project, we have a much more difficult assignment – we have at least 5 lineages, some of whom don’t share a MRCA for as many as 30,000 years.  Others are as close as 3,900 years.

My way around this is simply to treat our five lineages as distinct families and trace them accordingly.

This from Dr. Charles F. Kerchner, Jr.’s site. - “Mutation Rate: The rate at which a genetic marker mutates or changes over time... A typical mutation rate quoted in early (circa 2001/2002) Y chromosome STR (Y-STR) TMRCA calculations and analysis is one per 500 generations (transmission events). That would be an average mutation rate (Y-STR Genetic Clock Mutation/Tick Rate) of .002 or 0.2% per generation. Some commercial DNA testing labs are using an average Y-STR mutation rate of .003 or 0.3% per generation. And a 2004 study by FamilyTreeDNA indicates that the average mutation rate for all Y-STR markers for the male population as a whole may be twice as fast as the historical standard rate, i.e., .004 or 0.4% instead of .002 or 0.2%.”

But don’t get your hopes up. That basically means that now, instead of the average mutation happening once every 500 generations, it’s now once every 250 generations. The accepted duration of a generation is 25 years. So, even if you’re lucky, a genetic distance of 1 could mean you don’t share a common ancestor for 6,250 years. Of course, in our own project we know this isn’t correct and the DNA experts aren’t saying we should hold to this as a rule. As most say, any marker can mutate at any time. You could have several mutating.

In his own family project, Kerchner found that his family’s mutation rate is about once every 4.7 generations. “This is well, well within the time frame of when surnames were adopted and well, well within the time frame when the American colonies were settled, so one would not expect to see any random matches with different surnames. And in my Kerchner project I don't see any random matches at 37 markers to people with other surnames in the FTDNA database.” 

In our Sinclair project, the result is different. We do see some non-surname matches in our 37 marker results, but not in all the groupings or lineages. In the AMH group, we have some curious names, but I am certain these are non-paternity events (adoptions or otherwise) and not rapid mutation rates.

Because I know of at least one individual who will argue the case of abnormally faster mutation rates, I’m going to quote Kerchner’s analysis of the 25-marker test verbatim –
For my Kerchner Surname Project the 25 marker average haplotype mutation rate for ten people YDNA25 tested is .0042.  .0042 x 25 DYS STR markers = .105 per transmission event (birth of new Kerchner generation). (1/.105)=9.5.  Thus the longevity of the 25 marker Kerchner haplotype on average can typically survive unchanged about 9,5 generations (transmission events). This is well within the time frame of when surnames were adopted so one would expect to see few if any random matches with different surnames. And in my Kerchner project I don't have any random matches at 25 markers to other surnames in the FTDNA database.”

Thus, he’s saying that a genetic distance of 1 equals 2,375 years.

Kerchner goes on to say, “it is becoming increasingly important for surname project administrators to try to estimate the average Y-STR marker mutation rate and Y-STR haplotype mutation rates for the male line they are studying.”

”Someone asked me once. How do you do this if you don't know the MRCA ancestor for all your surname project members but your gut instinct and the traditional evidence and the similar haplotypes and surnames tells you that they are all probably related in the last several hundred years? Well if you don't know the ultimate common male ancestor and the ancestral haplotype you cannot do it directly.”

At Least Two of our Lineages Know Their MRCA

If you know your MRCA, and your DNA shows mutations, then this becomes important for the DNA study. Suddenly we can begin to learn more. Here are two. Stan and myself show mutations on 3 markers. FTDNA throws one of these out as it's now considered a super fast mutating marker (I think it's 464b). They say we have a genetic distance of 2. 

Niven and Ian Clennel are showing a distance of 3. They believe their MRCA is back in the 1400s. Now, this is not fully backed up by documents research as Ian is somewhat stuck in the early 1600s. However, there is a family story that points back to he 1400s and we have the DNA connection which is quite close. 

allele 385b 459a 464c
Niven 13 9 16
Ian 14 10 17
allele 439 464a 464b
Steve 11 16 17
Stan 12 15 16

Before I made this chart, it had occurred to me that these two lineages might be mutating on the same alleles and that others in our family might be doing this as well. I had thought I might find that our family does indeed have certain alleles that are mutating much faster than the norm, but this doesn't appear to be what's happening.  

The Case for Upgrading to the 67-Marker Test

Terry Barton of World Families was chatting with me one night, helping me solve a difficult question, and mentioned that, in choosing the alleles for the 67-marker test, FTDNA had selected a set of markers known to mutate at a particularly slow rate. For this reason, those who may think they're not well matched on the 25-marker test may find they line up very nicely on the 67. So while you could be matching only 20/25 with one of our Sinclair lineages on the 25-marker test, you may find you match 62/67 on the higher order test. That would be a significant match and would likely prove a MRCA within a timeframe of genealogical interest.

Welcome to Our Main Issue

We know for a fact that we have at least 5 lineages – Our Sinclair AMH Lineage is an average genetic distance of 8 from the S21 U106 Lineage. Even being generous, that distance means we don’t share a MRCA until back to the accepted MRCA of 3,900 years ago. So we will explore each lineage

Another suggestion by Kerchner is actually a method I invented for our project several years ago. He says, “...likewise one could put together a Y-STR marker haplotype set of 12 markers which mutated on average slower than the 12 marker panel offered by FamilyTreeDNA.” This is very close to what I did in my “Mutation Rate Study,” the chart with the yellow vertical lines on it that only looked at slower mutating markers (on the results page, behind the password). This one maintained our exact lineages with one exception and proved that we really are distinct lineages.

A Major Goal of the Sinclair DNA Project – Determining Our Mutation Rate

In the months ahead, I’ll be actively attempting to determine mutation rates within each of our known lineages. This will be done by verifying where possible the MCRA for each lineage or at least among those with a known MRCA like Stan and myself.

Sources – Website – “An Overview and Discussion of Various DNA Mutation Rates and DNA Haplotype Mutation Rates. Do the YSTR Haplotypes in some Y Chromosome Male Lines Mutate Faster Than in Other Male Lines?,” Charles F. Kerchner, Jr., P.E. (Retired) Written:  7 Jan 2005, Last Edit/Update:  17 Apr 2008, Copyright ©2005-2008  All Rights Reserved

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