Androgenetic alopecia is characterized by a loss of hair from the scalp that follows a defined pattern (Hamilton, 1951). It occurs in women as well as in men. It is caused by a shortening of the anagen (growth) phase and miniaturization of the hair follicle, which results in the formation of progressively thinner, shorter hair (Bergfeld, 1995). In men, the condition is often referred to as male pattern baldness (MPB) and appears to be androgen-dependent (Hamilton, 1942). The condition is hereditary, and follows a pattern that may be consistent with an autosomal dominant trait (Osborn, 1916).
Linkage evidence for an autosomal locus on 3q26 (AGA1) has been identified (Hillmer et al., 2008). See 300710 (AGA2) for a discussion of X linkage of androgenetic alopecia. A third locus has been found on chromosome 20p11 (AGA3; 612421). [from
OMIM]