There is a growing number of men with darker skin, and a growing body of research into how it affects the health of the human body is emerging to show the darkening process does not always result in the appearance of dark skin.
Dark skin is the most common genetic disease in men and women, with around 1.5 million people worldwide carrying it, and around 400,000 of those people suffer from a type of the disease known as melanoma, which can lead to skin cancer.
The condition affects around 10 per cent of the population, with the most affected in the developing world.
A 2012 study in the journal BMC Genetics found that dark skinned people had a higher risk of developing skin cancer, as did those with more melanin, the pigment found in skin.
There was no difference in risk between dark and light skinned men and a link was found between dark skin and lower IQ.
However, other studies have found darker skinned individuals had a lower risk of getting the rarer skin cancer known as squamous cell carcinoma, and those with darker hair and skin pigmentation were more likely to develop the condition.
In a new study, published in the American Journal of Human Genetics, researchers at the University of Oxford examined genetic mutations in skin pigments, skin cancer risk, and overall health in more than 700,000 European men and 60,000 women over a 16-year period.
“The genetic changes associated with dark skin were most strongly associated with those with high levels of melanin in the skin,” said Professor John Clements, who led the study.
Clements and his colleagues analysed the DNA of the genomes of 1,879 Europeans aged over 65, and found a significant number of them carried a mutation in the gene for melanin called MC2R, which codes for the melanin-specific gene M2R.
MC2R plays a crucial role in maintaining the melanocyte’s integrity and prevents it from dividing out.
Researchers also found that people with a mutation of MC2RE, which has also been linked to dark skin, were more than twice as likely to be diagnosed with melanoma.
This gene mutation is responsible for the formation of melanoma-like lesions in the outer skin, which are usually diagnosed in early-to-mid-life.
Professor Clements said that a mutation for MC2r was not just a problem for dark-skinned people, but for everyone.
“It can have a huge impact on how your melanin production is regulated, and the overall health of your skin,” he said.
Research is also emerging into the effects of melanocyte mutations, which may be a reason why dark-eyed men have a higher incidence of the condition than their white counterparts.
“This is not a new issue, but it has now been recognised that MC2s are associated with melanomas in different skin types,” Professor Clements told AAP.
Melanoma, also known as skin cancer or basal cell carcinomas, is the third most common skin cancer in the world, after melanoma and epidermal neoplasia, and affects up to 30 per cent in men.
It can cause long-term damage to the skin and lead to the development of a thickening of skin that can lead a person to develop skin cancer later in life.
Around 100,000 Australians are diagnosed with the disease each year.
More about dark skin:The darker skin is also associated with increased risk of melanomas, with one in three Australians carrying a mutation linked to the disease.
Some of the genetic mutations associated with the dark skin mutation have been linked with melanin producing melanocytes, which produce melanin.
When the skin cells produce melanins, they are able to pass on the melanins to the surrounding cells.
But, the melanosomes have a lower efficiency in producing melanin than the cells that produce melanoidin, a protein that allows melanin to be stored and released into the body.
Studies have shown that the more melanins a person has, the lower their melanocyte efficiency.
There is no cure for dark skin as it has a genetic component, but scientists are working to develop drugs that will target melanin and increase the efficiency of the melanocytes.