Figure 1.

Protein C gene SNPs. Protein C gene single nucleotide polymorphisms (SNPs) arranged in simplified haplotypes are illustrated. Each SNP is a colored column labeled with its 'rs' number. (For example, the NCBI [National Center for Biotechnology Information] website [123] can be searched by choosing the 'SNP' database and searching, for example, for 'rs2069912'. A wealth of data relevant to this SNP is then displayed.) The common (major) allele is illustrated in blue and the less common (minor) allele is displayed in yellow. SNPs are arranged in patterns called haplotypes. There are four common SNP patterns, or haplotypes, observed in the protein C gene. Haplotype 3 is the most common, making up about 40% of the observed haplotypes in those of European ancestry, whereas haplotype 2 makes up about one-third of the observed haplotypes. Haplotype 4 is the most similar to the haplotype observed in chimpanzees, and it is therefore considered the ancestral haplotype. The common haplotype 3 is similar to this ancestral haplotype on the left-hand SNPs, or 5' end, but differs significantly on the right hand SNPs, or 3' end. The 5' end of haplotype 1 is very similar to haplotype 2, which has evolved considerably away from the ancestral haplotype. However, 3' end of haplotype 1 is very similar to the ancestral haplotype 4. Therefore, there has almost certainly been a crossing over event that created this haplotype from two precursors. It is evident that much more information can be determined from haplotypes than from single SNPs.