SNPs are notably a type of common genetic variation; many SNPs are present in a large proportion of human populations [7]. SNPs typically have two alleles, meaning within a population there are two commonly occurring base-pair possibilities for a SNP location. The frequency of a SNP is given in terms of the minor allele frequency or the frequency of the less common allele. For example, a SNP with a minor allele () frequency of 0.40 implies that 40% of a population has the allele versus the more common allele (the major allele), which is found in 60% of the population.
