DNA polymorphisms are the different DNA sequences among individuals, groups, or populations. Polymorphism at the DNA level includes a wide range of variations from single base pair change, many base pairs, and repeated sequences. Genomic variability can be present in many forms, including single nucleotide polymorphisms (SNPs), variable number of tandem repeats (VNTRs, e.g., mini- and microsatellites), transposable elements (e.g., Alu repeats), structural alterations, and copy number variations. Different forms of DNA polymorphisms can be tracked using a variety of techniques; some of these techniques include restriction fragment length polymorphisms (RFLPs) with Southern blots, polymerase chain reactions (PCRs), hybridization techniques using DNA microarray chips, and genome sequencing. During the last years, the recent advance of molecular technologies revealed new discoveries of DNA polymorphisms. DNA polymorphisms are endless, and more discoveries continue at a rapid rate. Mapping the human genome requires a set of genetic markers. DNA polymorphism serves as a genetic marker for its own location in the chromosome; thus, they are convenient for analysis and are often used as in molecular genetic studies.
Part of the book: Genetic Diversity and Disease Susceptibility