Autosomen

Autosomen, or autosomes, are chromosomes that are not involved in sex determination. In most species with chromosomal sex, autosomes exist in homologous pairs in diploid cells and carry the bulk of genetic information unrelated to sex. Humans have 22 pairs of autosomes and one pair of sex chromosomes (XX in females and XY in males), for a total of 46 chromosomes in somatic cells. Autosomes are numbered 1 through 22 roughly in order of size and gene content.

Autosomes carry thousands of genes that influence a wide range of traits. Each autosomal gene typically has two copies, one inherited from each parent, and recombination during meiosis shuffles alleles to generate diversity. Inheritance patterns for autosomal traits include autosomal dominant and autosomal recessive modes, as well as multifactorial traits influenced by multiple genes and the environment.

Clinical relevance: Abnormal numbers or structure of autosomes can cause developmental disorders and congenital anomalies. Aneuploidies such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13) arise from nondisjunction. Many genetic diseases follow autosomal inheritance patterns rather than sex-linked patterns.

Evolution and variation: The exact number and content of autosomes vary among species, reflecting evolutionary rearrangements. While sex chromosomes determine biological sex, autosomes carry the majority of genes and regulate a broad spectrum of traits in an organism.