You may have noticed that your relatives who have light skin, red hair, and freckles have a tendency to get sunburned rather quickly. In the United States, people who fit that physical description might be called a “redhead”. In the UK, that person might be called a “ginger” (which is often meant as an insult). A recent study found that the “ginger gene” doubles the risk of melanoma.
A study that was published in JAMA Dermatology focused on the melanocortin-1 receptor (MC1R). It is the genotype that causes people to have red hair, freckles, and light skin. The study found that the MC1R genotype more than doubles the risk of melanoma.
To understand why, you need to gain some basic knowledge about melanin. Melanocytes are cells that manufacturer melanin. They make melanin-making enzymes and an amino acid called tyrosine. Melanosomes take in those enzymes and convert tyrosine into one of the two types of melanin that humans have.
One type is called eumelanin, which appears in people’s hair, eyes, and skin as a brown or black color. The other type is pheomelanin, which appears in people’s hair as a red or yellow color. People who have pheomelanin have light skin and may have freckles. They might have the MC1R genotype.
The darker form of melanin, eumelanin, provides a person with some protection against UV damage. People who have the lighter from of melanin, pheomelanin, lack that protection. It is very poor at providing protection from UV radiation.
The researchers who did the study first looked at mice who had the MC1R genotype. They prevented the mice from being exposed to UV. They found that the mice who had the MC1R genotype had an increased risk of developing melanoma – even though the mice had not been in the sun.
Next, the researchers looked at people who have the MC1R genotype. They judged a person’s sun exposure from having the person recall sunburns, and they also examined each person’s skin.
The researchers then attempted to determine the person’s risk of developing melanoma minus the damage from sunburns. From this, they concluded that people who have the MC1R genotype were 2.13 times as likely to end up developing melanoma than were people who did not have that genotype.
An editorial about the study was created by two of the researchers who worked on it: David E. Fisher, MD, PhD, and Elisabeth M. Roider, MD. In it, they note that among the individuals with the Fitzpatrick skin type 1, light skin, and red hair, more than 80% have a dysfunctional variant in both MC1R alleles.
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