Distribution of SNPs in intergenic regions relative to the start codons of predicted protein coding genes. The number of SNPs was plotted as a function of the distance to the initiation codon of genes using a window of 25 bases. Blue columns show the expected distribution based on the frequency distribution of 25 bases segments in intergenic regions. Red columns show the actual distribution. The two distributions are significantly different (Chi-square test, P 0.01).