Evaluation of DXS9902, DXS7132, DXS6809, DXS7133, and DXS7423 in humans and chimpanzees: sequence variation, repeat structure, and nomenclature.

Sequencing data obtained in this study provide information on the short tandem repeat allele structures of DXS9902, DXS7132, DXS6809, DXS7133, and DXS7423. Data were obtained from the three human major population groups, namely Africans, Caucasians, and Asians as well as from chimpanzees (Pan troglodytes). DXS7133 was found to be the most stable locus and DXS6809 seemed to have evolved from a simple array of CTAT units but currently reveals a highly complex and compound structure within and between humans and chimpanzees. DXS9902 results support a TAGA allele nomenclature, which increases in one repeat unit previously reported allele distributions at this locus. For DXS7132, human/chimpanzee comparisons performed in this study provided important evidence that the CTAT allele structure should be considered for allele nomenclature purposes. Also, possible population-specific intermediate type alleles (with Native American origin) were detected at this locus that could be useful for ethnic group differentiation. DXS7423 results revealed two different sequence structures and one of these structures seems to be restricted to a single allele class in just one population group (Africans).