ABSTRACT
The genetic diversity among individuals is a field of intense investigation, mainly because, in addition to harboring a record of human migrations, it explains the basis of inherited variation in disease susceptibility (Wang et al., 1998). About 90% of human variation has been ascribed to single nucleotide polymorphisms (SNPs) (Collins et al., 1998). SNPs are single base pair positions in genomic DNA at which different sequence (single nucleotide) alternatives (alleles) exist in normal individuals in some populations. In most cases SNPs are di-allelic, with two alternative bases occurring at an appreciable frequency (at least 1%). Tri-and tetra-allelic SNPs are rare in humans. Single base insertion and deletion variants, referred as ‘indels’, are not formally be considered to be SNPs (Brookes, 1999).
