autosomique

Autosomique, or autosomal, refers to the autosomes—the chromosome pairs that are not sex chromosomes. In humans, the genome comprises 22 pairs of autosomes and one pair of sex chromosomes (XX in females, XY in males). Autosomes carry the majority of an organism’s genes and are inherited independently of the individual’s sex, with traits and disorders transmitted through autosomal inheritance patterns.

Autosomal inheritance is categorized mainly as dominant or recessive. In autosomal dominant conditions, a single pathogenic allele can cause disease and affected individuals often have affected parents, with a risk of about 50% for each child if one parent is heterozygous. In autosomal recessive conditions, two pathogenic alleles are required, so carriers (who have one mutant allele) are typically unaffected; each child of two carriers has a 25% chance of being affected. Examples include Huntington’s disease (autosomal dominant) and cystic fibrosis (autosomal recessive).

Autosomal aneuploidies involve abnormal numbers of autosomes. Some trisomies are compatible with life, most notably trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome); others are usually not viable. The study of autosomal variation is central to medical genetics, with karyotyping and sequencing used to diagnose structural or numerical abnormalities, while genome-wide association studies (GWAS) investigate how autosomal variants contribute to traits and diseases.