Androgenic Alopecia - Genetics

Genetics

Since androgens and androgen receptors (AR) are the cause of androgenic alopecia, their genetic corollaries are a subject of much research. Some involved genes are X-linked, with men whose fathers show hair loss 2.5 times more likely to experience it themselves regardless of maternal report. The maternal line is crucial as well, however, as it contains the androgen receptor gene, which provides the necessary diathesis for androgenic alopecia.

The specific variant of the AR for baldness is on a recessive allele, so a woman would need two X chromosomes with the defect to show male pattern hair loss. The EDA2R gene on the X chromosome at Xq11-q12, close to the area which codes for the androgen receptor gene, has been suggested by some researchers as specific to androgenic alopecia. An allele on chromosome 3 at 3q26 also contributes.

Genetic causes of hair texture and non-androgenic hair loss have been discovered as well. One is P2RY5, mutations of which affect hair structure and woolly hair. Variants at this site can lead to baldness. Other research identified the gene SOX21, Y-linked, as related to certain non-androgenic alopecias.