Androgenetic Alopecia

By: Dave Blanchette
Biological Sciences Major
University of New Hampshire at Manchester
December 2011

An Introduction to AGA

Androgenetic alopecia (also known as AGA) is an inheritable polygenic condition where a very specific pattern of balding occurs. When expressed in males, this pattern gives AGA its more commonly known name: male pattern baldness. AGA is estimated to affect 35 million in the United States alone and by the age of 50 approximately 50% of men will show some degree of hair loss(7). The specific pattern seen in AGA begins with balding just above the temples and works directly backward toward the crown of the head where balding also begins. These two areas often meet to cause partial or complete baldness on the top of the head. Females exhibit a different pattern of balding that starts as a crease at the vertex of the head and spreads outwards in all directions.


Breeling, J. L. (2008, April 18). Retrieved from

As research on AGA's genomic components continues researchers have found several locations on multiple chromosomes that stand as risk factors and susceptibility loci. AGA is largely affected by the role of androgen and the androgen receptor gene (5). Polymorphisms within this androgen receptor (AR) gene have been recorded with direct linkage to the expression of AGA(5)(4). This wiki will take a closer look at the androgen receptor and AGA in hopes to understand more of this widespread condition.

Research Questions:

What role does the androgen receptor play in causing AGA?

Why are there so few known treatments for AGA?

Next: A look into the workings of the Androgen Receptor

(4)Ellis, J. A., Scurrah, K. J., Cobb, J. E., Zaloumis, S. G., Duncan, A. E., Harrap, S. B.Baldness and the androgen receptor: the AR polyglycine repeat polymorphism does not confer susceptibility to androgenetic alopecia.Hum. Genet. 121: 451-457, 2007.
(5)Ellis, J. A., Stebbing, M., Harrap, S. B. Polymorphism of the androgen receptor gene is associated with male pattern baldness. J. Invest. Derm. 116: 452-455, 2001.
(7)Hillmer, A. M., Hanneken, S., Ritzmann, S., Becker, T., Freudenberg, J., Brockschmidt, F. F., Flaquer, A., Freudenberg-Hua, Y., Jamra, R. A., Metzen, C., Heyn, U., Schweiger, N., and 13 others. Genetic variation in the human androgen receptor gene is the major determinant of common early-onset androgenetic alopecia. Am. J. Hum. Genet. 77: 140-148, 2005.