Androgenic alopecia (AGA)

Androgenic alopecia (AGA) is a non scarring, progressive miniaturization of the hair follicle which has a characteristic pattern of distribution (1).

• this is a common disorder affecting genetically predisposed men and women (1)
• the prevalence increases with age in both sexes (2)
• genetic factors determine age of onset and severity.

Hair loss is usually insidious, presenting as thinning rather than shedding.

In men

• tend to lose hair over the crown, along the frontal hair line, and the temples
• occasionally a female pattern of hair loss can be seen as well (1)
• type 2 5 alpha-reductase is to believed to be important in the development of male-pattern baldness.

In women

• hair loss over the frontal and central areas, but the parietal and occipital regions may be involved as well
• occasionally it may occur in a male pattern as well (1)

Reference:

• (1) Blume-Peytavi U et al. S1 guideline for diagnostic evaluation in androgenetic alopecia in men, women and adolescents. Br J Dermatol. 2011;164(1):5-15.
• (2) Schweiger ES, Boychenko O, Bernstein RM.Update on the pathogenesis, genetics and medical treatment of patterned hair loss. J Drugs Dermatol. 2010;9(11):1412-9