Autosomes are all chromosomes other than the sex chromosomes. In humans, all chromosomes, except the X and Y chromosomes are autosomes.

Normal human cells carry 44 autosomal chromosomes in 22 corresponding (homologous) pairs. In humans, the homologous autosomal pair is comprised of one autosome derived from mother, and the corresponding chromosome contributed by the father. Homologous autosomal chromosomes contain similar, but not identical genes. Although normal homologous autosomes contain the same genes (e.g., the gene for a particular protein) each may carry a different form of the gene (allele).

In addition to autosomes, normal human cells carry a pair of sex chromosomes. Females carry a pair of X chromosomes and males carry an X and Y chromosome).

During typical karyotype analysis, the autosomal pairs are ordered and numbered, from 1 to 22, in descending order of length (i.e., the longest homologous pair is labeled pair 1 and the shortest are labeled...