Did you know DNA influences freckle formation?
Genetic clues to why some of us have lots of freckles
Freckles – they fit the expression “the grass is always greener on the other side”, to a T. Those afflicted with these small spots want them gone often because of the teasing or bullying. And others want them so dearly, that they are even are willing to get permanent freckle tattoos. Freckles are one of those beauty marks whose inevitable appearance is strongly influenced by genetics. This is why we have very little control over the appearance of freckles, and why we can easily predict our chances of getting them based on our heritage.
Freckles may have set their own trend on Instagram, but they are far from being just a beauty mark to be adored. They are actually made of clusters of cells with melanin, a pigment in our skin that protects us from harmful ultraviolet (UV) rays. Sunlight triggers melanocytes, (cells in our skin), to make more melanin. Extra melanin is then transferred to the outer cells, called keratinocytes, making them appear darker. The more you expose your skin to the sun, the darker and more pronounced your freckles will become.
All of the variants linked linked to freckles are in genes related to melanin. There’s the MC1R gene that encodes the melanocortin 1 receptor found on the surface of melanocytes, which controls the production of melanin. The rs885479 and rs1805005 variants of MC1R result in an altered melanocortin 1 receptor protein and up to an 11-fold increased susceptibility to freckling.
The IRF4 gene makes a protein that controls other genes involved in melanin production. The rs12203592 version of this gene is strongly associated with the presence of freckles. BNC2 is another gene whose protein product regulates the levels of several other proteins linked to freckles. Studies in mice show that overproducing BNC2 leads to the loss of pigmentation.
Proteins encoded by two additional genes, ASIP and TYR, are both directly involved in melanin production. Tyrosinase (TYR) is the enzyme that starts off the process of making melanin. The ASIP protein binds and blocks the melanocortin 1 receptor, essentially turning it off. So it’s not surprising that variants in TYR (rs1042602) and ASIP (rs1015362 and rs4911414) are also linked to freckle formation.
Freckles occur more often on people with fair complexion, because freckles are a trait governed by the same genes that control the colour of our skin, hair, and eyes. We are well aware that red heads with pale skin probably need more protection from the sun, than someone with darker hair and olive skin. Hopefully, with the trends on Instagram, and celebrities (think Julianne Moore, Kate Moss or Emma Watson) doing their part to make freckles more acceptable, the day we truly embrace them for their beauty may not be too far off.