Quantifying genetic commonality

John E. Wiktorowicz, Ph.D. johnw at lynxgen.com
Wed Feb 28 15:52:15 EST 2001

I agree with the last statement. It is generally accepted that the actual
SNP frequency is more on the order of 1 SNP (1 nucleotide difference) per
about 1500 bp. This means that each of us has the potential to have at least
2,000,000 sites that express individuality. However, since most of the DNA
sequence is intergenic, much of this variability may not show up in the gene
products. So... the bottom line is that as a percentage of bp, the
variability is miniscule, but the effect is apparent.

> From: Joe Felsenstein <joe at evolution.genetics.washington.edu>
> Organization: BIOSCI/MRC Human Genome Mapping Project Resource Centre
> Newsgroups: bionet.molbio.evolution
> Date: 21 Feb 2001 20:16:58 -0000
> Subject: Re: Quantifying genetic commonality
> In article <96umk4$sfo$1 at mercury.hgmp.mrc.ac.uk>,
> Julian Assange  <proff at iq.org> wrote:
>> Nancy Bennett <nancyb at ignet.com> writes:
>>> My question is -- can anybody even wildly estimate the degree to which any
>>> two randomly chosen humans (or let's make it easier and say any two randomly
>>> chosen Europeans) are, in fact, genetically similar?  I recently read on the
>>> Human Genome Project web site that humans may have as few as "one gene in
>>> 500" that differs between individuals.  This would suggest that, on average,
>>> the genes at 99.8% of all loci are identical.  Is this an accurate
>>> estimate??
>> Yes, depending on what you mean by `gene' and `differ'. But it rarely
>> makes sense to talk about this data in absolute terms. You may have 19/20
>> positions correct for the state lottery, yet this does not mean you
>> have won 19/20ths of the lottery.
> I disagree.
> I don't think these figures are accurate.  The usual figure for
> the degree of difference between the DNA sequence of different
> individuals (let's be more precise -- between haploid genomes such as
> the sequences of two gametes) is 1 in 1000 bases (sometimes this
> is given as 1 in 500, it varies a bit).  But note that is bases, not
> genes.  Genes are not 1 base long.
> Two (haploid) human genomes are about 99.8% similar, counting bases.
> They do not have 99.8% of all loci identical.
> ---- 
> Joe Felsenstein         joe at genetics.washington.edu
> Dept. of Genetics, Univ. of Washington, Box 357360, Seattle, WA 98195-7360 USA
> ---


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