On the quantity and quality of single nucleotide polymorphisms in the human genome

Single nucleotide polymorphisms (SNPs) are useful markers for locating gene s since they occur throughout the human genome and thousands can be scored at once using DNA microarrays. Here, we use branching processes and coalesc ent theory to show that if one uses Kruglyak's (Nature Gen. 12 (1999) 139-1 44) model of the growth of the human population and one assumes an average mutation rate of 1x10(-8) per nucleotide per generation then there are abou t 5.7 million SNP's in the human genome, or one every 526 base pairs. We al so obtain results for the number of SNPs that will be found in samples of s izes n greater than or equal to2 to gain insight into the number that will be found by various experimental procedures. (C) 2001 Elsevier Science B.V. All rights reserved.