Male pattern baldness affects most men at some stage of their life. By the age of 70, 80% of all men will have started to go bald, with many men approaching the latter stages of hair loss by this time [1].
Lots of younger men worry about the fate that’s in store for their hair, especially if their dad is bald. While it’s true that hair loss is hereditary, it’s not always as simple as passing the linked baldness gene from father to son.
In this article, we’ll find out the facts about the baldness gene, including:
It’s a myth that there’s a single balding gene that directly determines whether or not you’ll go bald. Baldness is influenced by multiple genes, as well as other factors including diet, age, and general health [2]. One study found 63 different genes that play a role in androgenetic alopecia (AGA) [3].
When people talk about the baldness gene, they’re usually referring to the AR gene. The AR gene, or androgen receptor gene, is said to have the biggest impact on hair loss among men [4].
Everyone has the AR gene, regardless of sex, so it’s not the presence of this gene alone that triggers hair loss. Instead, variations within the gene control how sensitive your follicular androgen receptors are.
The AR gene controls the sensitivity of your hair follicles to dihydrotestosterone, a male sex hormone or androgen. Dihydrotestosterone, or DHT, binds to the androgen receptors in your follicles and causes them to shrink. So if your androgen receptors are highly sensitive to DHT, you’re more likely to go bald.
In addition, a high level of AR gene expression can result in more androgen receptors in your hair follicles. This can also contribute to hair loss.
You may be more likely to go bald if your dad is bald — but this isn’t always the case.
The AR gene is found on the X chromosome. In men, the X chromosome is inherited from your mother. That’s why many people believe the baldness gene comes from your mum’s side of the family.
Because of this, your maternal lineage is important when it comes to establishing whether or not you’ll go bald [5].
However, there are dozens of other genes linked with baldness that are located on the autosomes, Autosomes are non-sex chromosomes (i.e. they are not represented by X or Y).
Humans have 22 pairs of autosomes in addition to their XX or XY sex chromosomes. Within each pair, you inherit one autosome from each parent. Any hair loss gene on any autosome can put you at risk of losing hair, regardless of which parent it comes from.
As a result, it’s still possible for you to go bald if your dad is bald, even if you haven’t inherited the baldness variant on the AR gene from your mum.
In fact, one study found that 81.5% of sons with hair loss had fathers who were also bald [6].
Baldness on your mum’s side of the family may increase the likelihood of you developing early-onset pattern baldness [5]. That means you start losing hair before the age of 40.
Since all these genes on the autosomes also influence balding, it’s also not guaranteed that you’ll go bald if your mother’s father is bald.
Researchers are still examining the exact genetic mechanism that causes baldness. One study notes [5]:
“The average phenotypic resemblance should be greater between affected males and their maternal grandfathers than between affected males and their fathers.”
They also acknowledge that “family studies of AGA have typically stressed the resemblance of fathers and sons.” So more research is needed to determine how and why genes besides the AR gene influence baldness.
Ultimately, if other men in your family are affected by male pattern baldness, there’s a reasonable chance that you will be, too, regardless of whether they’re on your mum’s or dad’s side of the family.
Women are far less likely to have genetic hair loss than men, but the fact remains that lots of women are still subject to hereditary baldness. Approximately 30% of women experience female pattern hair loss by the age of 70 [6]. So how do baldness genes affect women?
Like men, all women have the AR gene. Unlike men, women have two X chromosomes and no Y chromosome, so they’re only affected by genes on the X chromosome. The AR gene can be inherited from your mother or father.
However, researchers have noted that some women develop female pattern hair loss in the absence of androgens, suggesting mechanisms independent of DHT may be in play [7].
Evidence has linked the CYP19A1 gene, also known as the aromatase gene, to genetic hair loss in women [8]. The aromatase enzyme converts androgens into oestrogens in the hair follicles, which may explain why female pattern hair loss is more likely to occur after menopause, as oestrogen levels drop.
Oestrogen may also help with male pattern baldness, as this hormone can limit DHT production in the body.
Back in 1916, a research study claimed that the AR gene behaved in an autosomal dominant manner in men, and an autosomal recessive manner in women [9-10]. That means the researcher believed just one copy of the AR gene could cause baldness in men, while women needed two copies — one from each parent — to experience genetic hair loss.
This theory is still valid [9-10]. However, researchers now agree that baldness is also influenced by several other genes. So it’s not as simple as whether the AR baldness gene is dominant or recessive.
Unfortunately, the only way to know if you’re susceptible to male pattern baldness is to wait and see. Frontal balding and temple hair loss are usually the first signs of male pattern baldness, and it can start at any age from late adolescence onwards.
Some men also see crown hair loss in the early stages of baldness, though this is less common. It’s usually a symptom of slightly more advanced hair loss, such as Norwood 3 or Norwood 4 balding.
A receding hairline is often the first sign of male pattern baldness. If you’re worried about your hair loss developing further, now’s a good time to get advice. Often, the earlier you tackle your hair loss, the cheaper and easier it is to maintain a thick head of hair.
Hair loss medications like Finasteride and Dutasteride stop DHT binding to the androgen receptors in your hair follicles. So these are some of the most popular treatments for those with male pattern baldness, especially if you’re in the early stages of hair loss and want to prevent further hair loss and promote new hair growth.
If your hair loss starts to progress further, a hair transplant is a great way to restore the hair you’ve lost.
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