Autosome

An autosome is a non-sex chromosome. It is an ordinarily paired type of chromosome that is the same in both sexes of a species. For example, in humans, there are 22 pairs of autosomes. The X and Y chromosomes are not autosomal. Non-autosomal chromosomes are usually referred to as sex chromosomes, allosomes or heterosomes.

Like other chromosomes, autosomes display STR and SNP mutations which can be observed and have been used in genetic testings for ancestry, ethnicity, race and genealogical purposes. Private testing companies which do autosomal STR tests include FamilyTreeDNA and DNAtribes. Whereas companies testing autosomal SNPs include AncestryByDNA and deCODEme.