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Male baldness

Hair loss is the loss of more than 100 hairs a day. Alopecia is a hair loss so important that the thickness of the hair is visibly reduced.

The limit between natural hair loss and pathologic hair loss is not precise. A certain quantity of hair loss is totally normal since each hair is constantly being renewed. During this regeneration, the “production site” of a hair, the hair follicle and it root, goes through a three-phase cycle:

  • Growth phase (anagen phase)
  • Transitional phase (catagen phase)
  • Shedding phase (telogen phase)

In the anagen phase, the hair is nourished from the root and grows. This cycle can last several years in healthy persons. During the growth phase, the cells are especially vulnerable to external factors. If this happens, this phase may be cut short.

During the catagen phase, which lasts only a couple of weeks, hair nourishment ceases and the cells stop dividing. The hair then enters in a rest phase (shedding), the telogen phase, lasting about four months. Towards the end of this period, the hair falls out and a new cycle begins. Alopecia can occur if the vital cycle of the hair follicle is altered.


The typical pattern of male pattern baldness begins at the hairline, which gradually recedes and forms an “M.” Eventually, the hair becomes thinner, thinner, and shorter and creates a U-shaped (or horseshoe) pattern of hair around the sides of the head.

Role of Genetics

Male baldness is a common disorder, affecting 40% of adult men and is a highly heritable condition, with a heritability of approximately 80%. The importance of male hormones in male pattern baldness is supported by the finding that a variation in the androgen receptor gene can reduce the age at which a man begins to lose hair and the degree of baldness.

The androgen receptor responds to signals from male hormones, such as testosterone and dihydrotestosterone. It is encoded by the AR gene, which resides on the X chromosome. The influence of various polymorphisms on male pattern baldness is reflected in the fact that baldness is often passed from father to son.


The extent of hair loss (alopecia) prevention depends on the cause. However, prevention is usually limited or impossible.

Neither androgenic alopecia nor alopecia areata can be prevented.

On the other hand, certain types of diffuse alopecia can be alleviated by a healthy and balanced diet. This prevents the development of hypoproteinemia and iron deficiency or other nutrients that promote hair loss.


  • AUTS2
  • HDAC4
  • SETBP1
  • PAX1
  • FOXA2
  • SLC14A2
  • EDA2R
  • AR
  • Xq12
  • LOC100270679
  • 20p11.22
  • HDAC9