Tandem repeats are repeated DNA sequences arranged together one after another. The total number of iterations can vary from site to site and person to person. In general, this group of repeats can be subdivided by size into four categories; megasatellite, satellite, minisatellite, and microsatellite. Some types are localized to specific sites, but others are dispersed throughout the genome.

Megasatellite DNA repeats range in size from 3-4.7 kb (kilobases) and have been identified on chromosomes 4, 8, 19 and the X. Their function is unknown.

The name satellite DNA was originally derived from the early buoyant density gradient centrifugation technique used to separate different size DNAs. This group of sequences formed a minor peak or satellite in the gradients. It is now known that the satellite DNA is primarily derived from the centromeric region of chromosomes and includes several different types of repeats ranging in size from 5-171 base...