This study shows an association between the gene that causes red hair and CMN. The gene seems to make CMN more likely to develop, particularly if the child has inherited a copy of the gene from each of their parents.
New research, using data from Children of the 90s (ALSPAC) at the University of Bristol, has identified that the gene causing red hair (MC1R) is more common in children with Congenital Melanocytic Naevi (CMN), a rare form of birthmark.
The research was carried out at Great Ormond Street Hospital (GOSH) and the UCL Institute of Child Health.
CMN are rare brown or black birthmarks which cover up to 80 per cent of the skin surface area. They can vary in size and number, and can occur anywhere on the body. The incidence of larger or multiple lesions is approximately 1 in 20,000 new births per year.
In the study published in the Journal of Investigative Dermatology , 166 people with CMN had their hair and eye colour recorded, and had their blood checked for the MC1R gene. Results were compared to a local control group of 60 unrelated children and with 300 UK children without CMN from Children of the 90s.
The changes in the gene causing red hair (MC1R) were found to be more common in children with CMN, and in their families, than those without the condition. In particular, children with CMN were much more likely to carry two copies of those changes, one from each parent. Researchers also identified that certain changes in the gene are associated with children having much more severe skin changes, for example a larger CMN, indicating that the MC1R genotype influences the development of these birthmarks when the child is in the womb.
Veronica Kinsler runs the paediatric pigmentary service at GOSH and has a weekly clinic for CMN. She explains: "CMN is a very rare condition, and currently there are no good medical treatments for it. In order to find treatments we need to understand what caused the birthmarks to occur in the first place, and therefore we are investigating the genetics of CMN.
"This study shows an association between the gene that causes red hair and CMN. The gene seems to make CMN more likely to develop, particularly if the child has inherited a copy of the gene from each of their parents. Also some variants of the gene are associated with the CMN being larger.
"If you have red hair in your family, these findings should not worry you, as changes in the red hair gene are common, but large CMN are very rare. So the changes do not cause the CMN to happen, but just increase the risk."
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