Autosomal dominant is a term used to describe a specific pattern of inheritance in genetics. It refers to a gene or trait that is present on one of the first 22 pairs of chromosomes and is dominant, meaning it only takes one copy of the gene to express the trait. Synonyms for autosomal dominant may include simply dominant, inherited in a dominant fashion, or expressed dominantly. Other similar terms may include Mendelian inheritance, familial inheritance, or molecular inheritance. These terms essentially mean the same thing as autosomal dominant and are used interchangeably in the scientific community to describe the same genetic phenomenon.