For male hair loss, androgenetic alopecia plays a dominant role, as it is responsible for 95% of cases. The genes that lead to androgenetic alopecia are the subject of research by scientists, but it has been shown that most of them are located on the X chromosome and are recessive. This is why it is thought that the mother is responsible for the development of hair in men.
For the same reason, the occurrence of androgenetic alopecia in women is rarer as it requires the presence of the abnormal (recessive) genes on both X chromosomes for them to be expressed and for the disease to occur. In men, where the sex chromosomes are XY, the presence of only one abnormal X is sufficient for the genes of androgenetic alopecia to be expressed.
The genes of androgenetic alopecia located on the X chromosome determine, among other things, the way the alopecia develops, as well as the speed of its progression. Women are less predisposed to androgenetic alopecia than men, but in women it usually occurs in the form of diffuse hair loss and does not lead to complete hair loss.
The most common pattern of male pattern of androgenetic alopecia is anterior and temporal thinning with a tendency to extend towards the top of the scalp. As Dermatologist – Venereologist Dr. Amalia Tsiatoura points out, 25% of men will develop thinning by the age of 30 and 50% by the age of 50.
Androgenetic alopecia in men is due to inherited sensitivity to the hormone dihydrotestosterone (DHT), which shrinks hair follicles and suppresses their growth, leading to a telogen phase that leads to hair loss.
Male pattern hair loss progresses rapidly at ages 20-30 years, with a gradual slowing down at ages 30-35.