Variants of the MC1R gene, associated with red hair, pale skin, and freckles, increases the number of genetic mutations related to skin cancer and the level of other gene mutations, further increasing the risk for skin cancer, a study published in Nature Communications has shown.1
Even a single copy of a red hair-associated MC1R gene variant increased the number of mutations in melanoma skin cancer; the most serious form of skin cancer. Many non-red haired people carry these common variants, and the study shows that everyone needs to be careful about sun exposure.
People with red hair make up approximately 1% to 2% of the world’s population. They have 2 copies of a variant of the MC1R gene, which affects the type of melanin pigment produced, leading to red hair, freckles, pale skin, and a strong tendency to burn in the sun.
“It has been known for a while that a person with red hair has an increased likelihood of developing skin cancer, but this is the first time that the gene has been proven to be associated with skin cancers with more mutations,” explained David Adams, PhD, joint lead researcher at the Wellcome Trust Sanger Institute in Hinxton, England.
“Unexpectedly, we also showed that people with only a single copy of the gene variant still have a much higher number of tumor mutations than the rest of the population. This is one of the first examples of a common genetic profile having a large impact on a cancer genome and could help better identify people at higher risk of developing skin cancer.”
This study involved analyzing publically available data sets of tumor DNA sequences collected from more than 400 people. They found an average of 42% more sun-associated mutations in tumors from people carrying the gene variant.
“This is the first study to look at how the inherited MC1R gene affects the number of spontaneous mutations in skin cancers and has significant implications for understanding how skin cancers form. It has only been possible due to the large-scale data available. The tumors were sequenced in the USA, from patients all over the world and the data was made freely accessible to all researchers. This study illustrates how important international collaboration and free public access to data-sets is to research,” explained Professor Tim Bishop, joint lead author and director of the Leeds Institute of Cancer and Pathology at the University of Leeds, West Yorkshire, England.
The study revealed that the MC1R gene variant both increased the number of spontaneous mutations caused by ultraviolet light and also raised the level of other mutations in the tumors. This suggests that biological processes exist in cancer development in people with MC1R variation that are not solely related to ultraviolet light.
1. Robles-Espinoza CD, Roberts ND, Chen S, et al. Germline MC1R status influences somatic mutation burden in melanoma. Nat Commun. 2016 Jul 12. doi: 10.1038/NCOMMS12064. [Epub ahead of print]