Skin Genetics

There are several genes known to be involved with skin pigmentation, these are: SLC24A5, MC1R, SLC45A2, ASIP, MATP, TYR, and OCA2. The most important of these genes in suspected order is SLC45A5 (solute carrier family 24, member 5), MC1R (melanocortin 1 receptor) and finally SLC45A2 (solute carrier family 45, member 2). So what does all that science jargon mean?

SLC45A5 – This is a gene which is located on chromosome 15. This gene is thought to be the cause of most of the difference in black Africans and white Europeans. This is due to only one variation in the 21420 base pair long gene. This is that one of the Alanines is changed into a Theanine, this is shown in the genetic variants of these two races. About 93+% of black Africans have the Alanine allele, where as 98+% of white Europeans have the Theanine allele. This single difference is thought to be the responsibility of the 25% – 38% change in the melanin index between the two races. The link between this gene and skin colouration was discovered while experimenting on what causes the difference in colour on Zebra Danios (a tropical fresh water fish).

MC1R – This gene is commonly known as the Agouti gene, Variations of this gene control melanogenesis the production of melanin within living cells. This means that the gene not only controls the level of pigmentation in your skin, but it also controls the colour of your hair! The variants in red headed people cause very little melanogenesis compared to the variants in people which tan well.

These variants are also responsible for the susceptibility people have for melanoma skin cancers, increase your chances of getting freckles and solar lentigines. On the plus side, some variations of MC1R have been known to increase the amount of pain which is taken away when morphine is used.

SLC45A2 – While this gene does not play a major part in the pigmentation of humans in general, variants of this gene can cause very dramatic changes of pigmentation. Notably oculocutaneous albinism. This is a form of albinism involving the eyes and skin, however some definitions will say it includes the hair. These variants cause varying levels of disruption to melanin production; all of these variants are recessive so you may unwittingly be a carrier.

What else is there in your genes which effects your skin?

BRAF – Variations of this gene are present in 70% of malignant melanomas, it is only a change of one base pair which prevents this gene from turning on and off normally. If you are worried about any odd shaped mole do see your doctor quickly, melanomas are easy to treat when caught early but are often left too late to be dealt with effectively! It is also important to have them removed as alterations in the BRAF gene encourages cancerous growth in other parts of the body.

PKP1 – Mutations in Plakophilin 1 are most commonly associated with skin fragility syndrome (ectodermal dysplasia). Skin fragility syndrome can make patients hyper sensitive to sunlight, very pale and cut/tare easily. However these cuts do not heal normally, because when the scar develops the new skin becomes almost translucent for a up to several months depending on the severity of the condition and injury.