Dr. Bertram Medical Hair Transplant 眉 髮 醫 學 移 植 中 心 ( 香 港 )
( 852 ) 3421-1138
5 α Reductase & DHT
Circulating Testosterone enters a hair follicle
The Testosterone is converted by 5 α Reductase into DHT
DHT binds to Androgen Receptor and cause miniaturization
(pictures from Dr Stough's Textbook "Hair Transplantation")
Androgen Receptors (AR)
AR protein mediates the action of androgens (male hormones) including testosterone (T) and DHT. Once activated by an androgen it translocate into the nucleus of a cell, where it acts as a transcription factor responsible for the transcription of other genes.
Androgen Receptor Genes
These are the DNA regulator of AR and are targeted by the HairDx Genetic Test. The genes are found in :
X-chromosome - the major susceptible gene for AGA
Several other genes e.g. the short arm of chromosome 20
Diydrotestosterone ( DHT )
DHT is a by-product of testosterone converted by Type II 5 α reductase. Although all androgens can cause miniaturization in men, DHT has highest affinity for the hair follicle Androgen Receptors. Skin and follicles in balding scalp contain more DHT than non-balding scalp. Prolonged DHT exposure leads to miniaturization.
DHT also causes acne, facial hair, and enlargement of the prostate(BPH). Kaufman in 2002 showed that DHT have no known beneficial role after puberty and can be targeted specifically without significant concern.
5 α Reductase
There are 2 types of 5 α Reductase: Type I & II. Type 1 is found in all body skin and scalp, while Type II is found in genital skin, prostate, and other genital tissues.
Dr Inaba suggested that 5 α Reductase is contained within the sebaceous glands of hair follicles. Over-consumption of animal fat may stimulate the sebaceous gland and thus 5 α Reductase leading to early onset of AGA.
Some part of the world population has no 5 α Reductase. Consequently they have no prostate or hair loss problem.
