Archiver > GENEALOGY-DNA > 2010-03 > 1268632318

From: "Tim Janzen" <>
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA
Date: Sun, 14 Mar 2010 22:51:58 -0700
In-Reply-To: <SNT115-W196CFB24CCDD653D7C3D50CC2E0@phx.gbl>

Dear Steve,
We still don't know the true average number of Y SNPs that occur per
generation, but it appears that in general in any given lineage that Y SNPs
are occurring with a frequency of between one every 3 to 6 generations. See
09 and
92. As we move into complete Y sequencing more and more in the next several
years, improving the accuracy of the sequencing of the Y chromosome will be
important and will help reduce the frequency in which erroneous SNPs that
are reported need to be tested in other people. As Ken mentioned, there are
a lot of relatively private SNPs that have occurred within the past 500-1000
years that are still awaiting discovery.

-----Original Message-----
[mailto:] On Behalf Of Steven Bird
Sent: Sunday, March 14, 2010 9:31 PM
Subject: Re: [DNA] Clades, Definitions, Discoveries, FTDNA

There were 134 million births last year, according to the U.N. estimates.
Half of these were boys, so about 67 million boys. The odds of a SNP
occurring, according to Hartwell 2008, are 1 in a billion. That means that
there is just a 6.7% chance of a Y-SNP occurring within ONE birth among
those 67 million boys last year. Following your logic, on average, ONE new
SNP occurs among all births every 15 years or so. However, since the new
SNP is always de novo and can occur anywhere, and there are 3 billion base
pairs in the human genome, the odds of any one SNP being duplicated are 3.0
* 10 to the -17 power.

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