SNPs are the most abundant form of genetic polymorphisms found in the human population and have become a focal point in the study of the genetic basis of multifactorial diseases and traits (see Article 57, Genetics of complex diseases: lessons from type 2 diabetes, Volume 2), interindividual differences in response to therapeutic drugs (“pharmacogenomics”), and human evolutionary and population history (see Article 71, SNPs and human history, Volume 4). Sources of polymorphisms within DNA sequence include variable numbers of tandem repeats (VNTRs) such as microsatellite repeats and short tandem repeats (STRs), small insertions and deletions of sequence (in/dels), gene copy number variation (Sebat et al., 2004 Fredman et al., 2004), and single-nucleotide polymorphisms (SNPs) (Kwok et al., 1994). Such genetic variation, that is, differences in DNA sequence among a group of individuals or between populations, occurring with frequency >1% is known as genetic polymorphism. This information is becoming available in public databases and will allow researchers to identify and characterize naturally occurring variations in the human DNA sequence across individuals. Worldwide research efforts to characterize the human genome, such as the Human Genome Project (see Article 24, The Human Genome Project, Volume 3), the ENCODE project, and the International HapMap Project, along with advances in DNA sequencing technologies, have produced an enormous amount of DNA sequence information.

Macvector assemble plasmid