Autosomal dominant inheritance is a mode of genetic inheritance in which a single copy of a mutated gene is sufficient to cause a trait or disorder. It is the most common form of genetic inheritance in humans. Autosomal dominant inheritance affects both sexes equally and is passed from generation to generation in a predictable pattern. In some cases, the trait or disorder can be passed from a parent to a child without the parent even knowing they have it.
In autosomal dominant inheritance, the mutated gene is usually located on an autosome, which is one of the 22 pairs of chromosomes that are not the sex chromosomes. The gene is passed from parent to child in a predictable pattern known as Mendelian inheritance. In Mendelian inheritance, each child has a 50% chance of inheriting the mutated gene from the parent who carries it.
When a mutation is autosomal dominant, it means that the mutated gene is expressed even when only one copy of the gene is present. This is because the mutated gene is dominant over the normal gene. As a result, a person who has one copy of the mutated gene will express the trait or disorder, while a person who has two copies of the mutated gene will express the trait or disorder more severely.
Most traits and disorders that are inherited in an autosomal dominant pattern are caused by a mutation in a single gene. Examples include Huntington’s disease, Marfan syndrome, and Neurofibromatosis type 1.
In some cases, autosomal dominant inheritance can also be caused by a chromosomal rearrangement, such as an inversion or a duplication. These chromosomal rearrangements can cause the gene to be expressed at a higher level than normal, resulting in a trait or disorder.
Although autosomal dominant inheritance is the most common form of genetic inheritance in humans, it is important to remember that not all traits or disorders are inherited in this way. Some disorders, such as Down syndrome, are caused by a chromosomal abnormality and are not inherited.
References
Bell, J.G., & Coble, J. (2017). Human genetics: Concepts and applications (10th ed.). New York, NY: McGraw-Hill Education.
Hartl, D.L., & Clark, A.G. (2015). Principles of population genetics (4th ed.). Sunderland, MA: Sinauer Associates.
Thompson, E.A., & Easton, D.F. (2020). Autosomal dominant inheritance. In Genetics Home Reference. Retrieved from https://ghr.nlm.nih.gov/primer/inheritance/autosomaldominant