Autosome

This article is about a type of chromosome. For the ancestral discovery method using autosomal DNA, see Genealogical DNA test#Geographic origin tests.

An autosome is a chromosome that is not a sex chromosome, or allosome. For example, in humans there are 22 pairs of autosomes and one allosome pair. XX and XY are the 23rd chromosome pair which determines sex, female (XX) or male (XY).

Human chromosomes
Female (XX)	Male (XY)
There are two copies of each autosome (chromosomes 1-22) in both females and males. The sex chromosomes are different: There are two copies of the X-chromosome in females, but males have a single X-chromosome and a Y-chromosome.

See also

• Autosomal dominant
• Autosomal recessive
• Homologous chromosome
• XY sex-determination system