2022/02/24

Red hair is caused by a broken gene

It's called a mutation, a variant, SNP or polymorphism - Actually it's a genetic error


Polymorphism? A variant?

https://medlineplus.gov/genetics/gene/mc1r/

Excerpt: "Common variations (polymorphisms) in the MC1R gene are associated with normal differences in skin and hair color. Certain genetic variations are most common in people with red hair, fair skin, freckles, and an increased sensitivity to sun exposure. These MC1R polymorphisms reduce the ability of the melanocortin 1 receptor to stimulate eumelanin production, causing melanocytes to make mostly pheomelanin. Although MC1R is a key gene in normal human pigmentation, researchers believe that the effects of other genes also contribute to a person's hair and skin coloring.

The melanocortin 1 receptor is also active in cells other than melanocytes, including cells involved in the body's immune and inflammatory responses. The receptor's function in these cells is unknown."


Excerpt: "Pain sensitivity has been linked to the melanocortin-1 receptor (MC1R) gene. A mutation in MC1R can result in pale skin and red hair in humans and may modulate pain responses in general. Human studies have shown that women with non-functional MC1R’s were sensitive to experimental induced cold and heat pain. A study demonstrated that females with red hair required higher dose of anesthesia than females with dark hair to experience analgesia to electrical stimulation. Moreover, women expressing non-functional MC1Rs display greater analgesia from opioid analgesia. If redheads in general respond differently to pain and analgesics, this is of clinical importance."

SNP?

https://link.springer.com/article/10.1007/s00439-010-0939-8

"MC1R SNPs are fairly indicative for red hair and thus have already been implemented in forensic science."

It's a broken gene


Excerpt: "Summer is coming and I would like to get rid of my red hair and fair skin. Is there any way to fix my broken MC1R gene?

-A curious adult from Poland

May 7, 2015

Hi curious adult from Poland! I’m sorry to say the short answer to your question is no we can’t (at least not right now). Sunscreen and the right clothing are still your best bet this summer.

We can’t really fix the broken MC1R gene responsible for your red hair (and fair skin) for a couple of reasons. First off, we are not very good at fixing broken genes yet.

Gene therapy (as fixing broken genes is called) doesn’t work very well and is dangerous to boot! The cure might be worse than the condition in this case. Second, the situation with MC1R is surprisingly complicated. If we could fix your gene, there may be a shot at getting rid of your red hair. But the fair skin is much trickier. No matter how hard we try we may not be able to get rid of that.


...In your case, even if we get the gene in, we still can’t be sure of the results. As you likely know, the protein made by the MC1R gene is important for making pigments in our skin and hair. A mutated gene leads to lighter pigments, in your case red hair and fair skin.

Like most of the rest of our genes, we have two copies of our MC1R gene. We got one copy from our mom, and one from our dad.

Typically, you need both of your MC1R gene copies to be of the red type to have red hair. (This is called a recessive trait.) So, having one not-red MC1R gene around would mean bye-bye red hair, right? Well not exactly. Sometimes people who have one, or even two, not-red versions, still have red hair!. So, adding in the new copy may not mean good-bye red hair."

"


"Gene mutations that lead to a loss in function are associated with increased pheomelanin production, which leads to lighter skin and hair color. Eumelanin is photoprotective but pheomelanin may contribute to UV-induced skin damage by generating free radicals upon UV radiation. Binding of MSH to its receptor activates the receptor and stimulates eumelanin synthesis. This receptor is a major determining factor in sun sensitivity and is a genetic risk factor for melanoma and non-melanoma skin cancer."

MC1R mutations lead to a weakened immune system

https://pubmed.ncbi.nlm.nih.gov/30278967/

Excerpt: "This is the first study to demonstrate a significant association between genetic polymorphisms and a nonfatal burn-induced SIRS complication. Our findings suggest that MC1R polymorphisms contribute to dysfunctional responses to burn injury that may predict infectious and inflammatory complications."

https://europepmc.org/article/med/25155575

Excerpt: "Persons with red hair have mutations in the MC1R causing its inactivation; this leads to a paucity of eumelanin production and makes red-heads more susceptible to skin cancer. Apart from its effects on melanin production, the α-MSH/MC1R signaling is also a potent anti-inflammatory pathway and has been shown to promote antimelanoma immunity. This review will focus on the role of MC1R in terms of its regulation of melanogenesis and influence on the immune system with respect to skin cancer susceptibility."

Papers about MC1R connections to the immune system:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758465/
https://www.frontiersin.org/articles/10.3389/fphar.2018.01535/full
https://www.nature.com/articles/s41598-020-64305-9

Summary and conclusions:
  • Red hair is often explained as normal genetic variation, a gene allele, a SNP, a variant or so called polymorphism.
  • We are taught that definition of evolution is change in allele frequency.
  • Actually MC1R mutations (change in allele frequency) are genetic errors resulting in loss of function and a weakening immune system.
  • The MC1R gene is widely used for several purposes in human cells. As in pigment production, it is also necessary for a properly functioning immune system.
  • Human DNA is organized in highly sophisticated way; it doesn't tolerate mutations (genetic errors).
  • Having a MC1R mutation doesn't always predict red hair. MC1R only explains 73% of the SNP heritability for red hair in UK Biobank.
  • MC1R mutations are examples of genetic entropy. They have nothing to do with assumed evolution.
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