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Archiver > GENEALOGY-DNA > 2010-03 > 1268616551


From: Michael Maddi <>
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
Date: Sun, 14 Mar 2010 18:29:11 -0700 (PDT)


Steven Bird wrote:

>
> So if a SNP shows up at the same location as L21 on the y chromosome and has the same change in nucleotide base as L21, but occurs in a man SNP-tested as in haplogroup J1, does that make that man a member of the R-L21 clade?

That really is not going to happen. The mutation rate for SNPs is on the order of 1 time 10 to the negative 9th per generation. The whole point of a SNP is that it is a one time mutational event in human evolutionary history, occurring at one base pair out of about 3 billion base pairs total in the human genome, that will be passed down to all descendants of that individual. L21+ will only have occurred in the descendants of the first individual to have L21, the common ancestor. The man in J1 will not have this polymorphism.

My reply:

In fact, it's happened multiple times. When a parallel SNP mutation is discovered in a different haplogroup than the original discovery of the SNP, the original discovery has a ".1" added to the SNP name and the new SNP discovery has ".2" added to the SNP name.

For an example of this, go to ISOGG's SNP index at http://www.isogg.org/tree/ISOGG_YDNA_SNP_Index.html and search for L65. You'll find that there is L65.1 (SNP for I2b2) and L65.2 (SNP for J1c3d1a). Look at the last column for those two SNPs and you'll see that they occur in the exact same location on the y chromosome. There are other examples on that page of SNPs with a .1 or .2 suffix that represent parallel SNP mutations in different haplogroups, for instance M64.1 and M64.2.

Mike Maddi







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