The Genetics of Hair Loss

Ever looked at your parents and thought how lucky you were that they had a full head of hair only to realise that one day your own hair was starting to thin?

You might attribute your receding hairline to anything from stress, the horrible flu you had last month or even from wearing a cap every weekend, but unfortunately it’s still probably related to something a lot less controllable your genes.

Areas of the scalp that can be affected by genetic hair loss male female pattern baldness men women Areas of the scalp that can be affected by genetic hair loss in both men and women


Polygenetics of Pattern Hair Loss

Genetic hair loss is known as androgenetic alopecia but is often referred to as male pattern baldness or female pattern hair loss.

The biology of androgenetic alopecia is complex but if we’re talking basics, it involves an inherited sensitisation of genetically predisposed hair follicles to the hormone dihydrotestosterone (DHT). The affected hair follicles gradually shrink and the hair life-cycle shortens which results in thinning hair. In some cases the follicle eventually ceases to produce hair, shuts down and becomes dormant.

Until fairly recently it was believed the genetic tendency toward hair loss came from a gene on the X chromosome inherited from the mother’s side of the family. However, whilst other studies have shown the propensity is more likely to be inherited from our fathers, androgenetic alopecia is actually a complex condition and most likely the result of effects from several genes.

Scientists confirmed the polygenetic theory with the discovery of two other genetic variants, completely unrelated to the gene on the X chromosome, which increase the risk of hair loss. Since then, additional genes thought to contribute to our likelihood of developing pattern hairloss have been discovered as researchers continue to learn more about human DNA.

The additional genes that have been identified can be inherited from either or both sides of the family; whilst there are no official figures for women, research following the discovery of the first two additional genes showed that one in seven men are at risk of inheriting all three genetic variants, effectively increase their risk of hair loss sevenfold.



Likelihood of developing genetic hair loss can increase with age

Androgenetic alopecia can start any time following puberty and up to half of the male population will be affected by the time they are 50 years of age. This figure jumps to 80% by the time men reach 70.




Almost half of all women will, at some point in their lives, experience some form of hair loss but there is no official figure for female pattern baldness specifically, though it is widely considered that the majority of women affected by androgenic alopecia may not notice any hair loss until menopause. It could be the drop in oestrogen levels at menopause that leave women more susceptible to the effects of testosterone but some scientists have also noted up to 30 different hormones could play a part in female pattern hair loss (as opposed to just DHT).

“The difference in figures is partly because women’s hormones are not as high as men’s,” says Leonora Doclis, senior trichologist at the Belgravia Centre. “But there was also an understanding that a woman would need to inherit the tendency from both sides of the family.”

One study showed that for women with female pattern hair loss, the incidence of androgenetic alopecia in immediate male relatives aged 30 years-old or over, was 54% and in female relatives older than 30, it was 21%.

The difference in the appearance of hair loss due to androgenetic alopecia between men and women is evident but not easily explained. DHT is an androgen (male sex hormone) but is produced by both men and women. Perhaps the fact that generally men produce more testosterone than women could explain the earlier onset and more extreme symptoms.

“This could be partly true but the specifics are unknown so experts have agreed to term them differently because, although they are both hereditary forms of hair loss, the patterns are so different,” Leonora notes.

"Men will notice defined areas are affected - such as a receding hairline, the formation of a bald patch on the top of the scalp and gradual thinning on the crown that could eventually lead to baldness. Women instead notice a gradual thinning all over the top of the scalp and a wider gap where the hair parts, but very rarely experience baldness."

Luckily, for both men and women with hereditary hair thinning there are non-surgical hair loss treatments available, including MHRA licensed and FDA approved medications. These can be used alongside hair growth supporting products to help stimulate the follicles and encourage the maintenance of normal healthy hair growth.













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The Belgravia Centre

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