Re: How many genes do we differ on?

Date: Fri Feb 16 2001 - 16:08:57 MST

Robin asks,
> Anyone seen the answer to this question: On how many
> genes do two typical humans differ?

According to what I have read, the primary causes of variability between
humans are what are called SNPs, Single Nucleotide Polymorphisms.
These are places where different people's version of a gene varies in a
single nucleotide. I have an A, you have a G. According to an L.A. Times
article on Monday, SNPs account for about 85% of genetic variation.

Genome researchers have identified approximately 3 million SNPs in the
human genome. The data is still incomplete and some project that there
could be as many as 10 million SNPs. However, according to the same
article, the "overwhelming majority" of SNPs identified so far are not
in gene-coding portions of the genome. They don't give a figure for
what that means as far as SNPs that affect genes.

Even if we know on how many places people can differ potentially, that
does not answer Robin's question, which is on how many of those places
two randomly chosen people would actually differ. No doubt it would
depend on how closely related the people are, and perhaps on whether
they are from the same part of the world or the same ethnic group.
But I have not seen any figures on this. Possibly they will not be
available until more people have been sequenced.


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