Generally, we all accept greying hair as a rite of passage - it’s natural and is bound to get us all at some point in our lives! However, when you’re standing in front of the mirror and find some strands of grey hair, the acceptance may well go out of the window. It’s not so exciting anymore, and for some, rather stressful.
In discussions with friends and family, lifestyle - mainly diet and stress - are often labelled as the reasons to blame. But the great, or perhaps not so great, news is that your genetics may also play a role.
Unfortunately, the solutions to greying hair are sparse and mainly temporary - hair dye! But with a global pandemic raging, and our beloved hairdressers closing their doors (albeit temporarily), people are starting to own that grey hair. And why shouldn’t we? Grey hair is actually incredibly common.
Epidemiology of grey hair
Dermatologists follow the 50/50/50 rule of thumb for greying hair epidemiology. But what is the 50/50/50 rule?
According to this rule, half (50%) of the population will have lost 50% of the colour in their hair, by the age of 50 . However, in a 2012 study with 4,192 healthy volunteers, it was observed that 74% of people had grey hair between the ages of 45 and 65 years of age.
The greying “problem” affects some of us earlier than others. Our daily habits, certain diseases, and nutritional deficiencies can all play a role in early-onset greying. As we have mentioned already, our genes also play a role in premature greying.
Fun fact: Our hair does not “change” colour to grey but instead loses colour (melanin) and therefore transitions to the colour grey.
Melanocytes are central to understanding greying
The colour of our hair is the result of pigment (melanin)-producing cells known as melanocytes. During the natural hair cycle, some melanocytes become damaged and die. If there is no melanocyte stem cell in the hair follicle to replace this dead or damaged cell, the pigment production ends and the hair turns grey .
In other words, hair greys due to an absence or malfunction of the colour-producing melanocytes. In theory, replenishing melanocytes would restore hair colour.
The genetics of greying
Scientists are still studying the science behind going grey. More specifically, research is underway to study the effect of a person’s genetics, lifestyle, stressors, etc. on their likelihood of greying early. To date, a handful of genes, some diseases and deficiencies, and lifestyle choices have been implicated.
You would expect that studying grey hair would be easy considering how incredibly common it is. However, this is not the case because of confounding variables such as hair dyeing.
Understanding the link between greying and genetics has been difficult to measure. Identical twin studies provide interesting insight -- as identical twins go grey at a similar age, rate, and pattern. For this reason, it is suggested that this trait is influenced by the combination of effects at multiple genetic locations.
Despite knowing this for years, scientists have only identified one gene that is definitely associated with age-related greying in humans. This gene, called the IRF4, is a marker for premature greying .
So... what do you need to know about the IRF4 gene?
The IRF4 gene
The IRF4 gene is the first gene that has been found to be associated with hair greying. This gene is important in bringing colour to our hair via the process of melanogenesis i.e., the making of melanin by special cells called melanocytes.
This gene directly controls another gene called TYR, which codes for tyrosinase, a very crucial protein involved in melanogenesis. Without this protein, our body would be unable to produce melanin, a pigment molecule that gives hair its colour.
More specifically, the first step of melanogenesis involves the conversion of a molecule called L-tyrosine to another molecule called DOPAquinone. This first step depends on the tyrosinase protein. Without the tyrosinase protein the remaining steps involved in the conversion of DOPAquinone to melanin will remain incomplete .
As we have discussed in previous reports, an individual inherits two copies of every gene from their biological parents; one inherited from each parent. If an individual inherits even one copy of the T variant on the IRF4 gene, the individual has a higher risk of greying compared to an individual that inherits two copies of the C variant (CC genotype).
In this case the T variant is the “risk allele”, i.e.it increases the likelihood of an individual having grey hair. According to one study conducted in Poland, the occurrence of the T allele increases the probability of grey hair in individuals with 1 or 2 copies by 27.3%. Comparatively, someone with 2 copies of the C variant has a 12.5% chance of greying under the age of 30 . It is worth noting that the exact risks associated with each copy of the T variants are currently unknown and research to quantify the effect of this variant is still ongoing.
Until further information becomes available, let’s bask in the good news knowing that the C variant is more common in the general population, with approximately 86% of people carrying at least one copy .
In other positive news, the rs12203592 variant on the IRF4 gene is only able to explain around 8% of cases of greying.
This means that there are also many other causes of premature greying. In fact, one particular study went so far as to find 127 differentially expressed genes in the follicular cells of grey hair . Recent analyses suggest that hair greying only exhibits 27% heritability, although other research suggests hair greying has up to 90% heritability.
Most of those 127 differentially expressed genes were associated with the pigmentation pathway. Other genes that play a central role in melanogenesis (i.e. the pigment producing process) have also been implicated in early-onset greying. For example, variants, mutations or malfunctions of the TYR gene can also cause greying, as in the case of albinism .
Although the cause of hair greying has been extensively studied, insights in the area are few and far between. As a result, the exact mechanism of greying is poorly understood, highly complex and may involve various mechanisms. Research in the area is still ongoing.
Other factors linked to greying
Apart from genetics, there are many other factors that may be causing early-onset greying.
This includes (but is not limited to) stress , nutritional deficiencies, a person’s lifestyle, and conditions such as alopecia and vitiligo. However, because many different factors may be involved in greying, it is particularly difficult to calculate the effect of each of them on the greying process.
Lifestyle factors like smoking have also been associated with accelerated ageing, as characterised by wrinkling and grey hair. Individuals with nutritional deficiencies , particularly low levels of B vitamins, vitamin D, iron, and others have been associated with early-onset greying.
What can you do about it?
Once hair goes grey, there is little one can do to reverse the colour change, however, there are some things you can do to slow down the greying process. For starters, managing your stress and eating a balanced diet may help prevent premature greying. Saying goodbye to tobacco and cigarettes will also help prevent early greying (it’ll also help prevent a number of serious health conditions).