Androgenetic alopecia is a type of hair loss that is inherited from either or both the mother and the father. Also known as male- or female-pattern hair loss, it is the most common cause of hair loss.
The condition occurs when the growth (anagen) phase of the hair growth cycle becomes shorter and shorter. A genetic sensitivity to androgens, a type of hormone, causes hair follicles—where hair growth begins—to sprout hairs that are thinner than normal. The hairs become thinner and thinner, and eventually the follicles die away.