“Early-life UV exposure that confers risk for melanoma also plays a role in development of moles or melanocytic nevi, which can be both a biomarker for melanoma risk and occasionally an immediate precursor,” said Neil Box, PhD, investigator at the University of Colorado Cancer Center and assistant professor in the Department of Dermatology at the CU School of Medicine in Denver.
The study showed that children with certain combinations of the blue eye-color gene variant and genetic variants that cause red hair are particularly susceptible to the formation of freckles and moles as they take waterside vacations early in life.
“Our research demonstrates that longitudinal studies are a powerful way to find and characterize gene-environment interactions,” Box said. “These findings are an important step toward identifying high-risk groups for melanoma based on genotype and sun exposure history.
“Our data could potentially help produce refined guidelines or recommendations for UV exposure behaviors in genetically high-risk children,” Box added.
Box and colleagues used DNA samples and information about sun-behavioral patterns from 477 non-Hispanic or Hispanic white children to evaluate the effect of different levels of sun exposure on mole and freckle formation in relation to genetic factors known to be associated with melanoma.
Following the children’s behavior from 2004 to 2008, the researchers discovered that the number of moles and freckle density increased among the children in each successive year. Additionally, total number of sunburns, waterside vacations, and chronic sun exposure increased each year. All of the measures of sun exposure contributed to increased freckle counts, and cumulative chronic UV exposure was a major driver of freckle development.
“We also found that children who are homozygous for the major blue eye-color gene variant are particularly susceptible to formation of moles as they take more waterside vacations in early life,” Box said. “Those kids with certain combinations of the blue eye-color variant and genetic variants that cause red hair color were also more likely to have larger moles as they sustained more sunburns.”
The study also demonstrated for the first time that children who have particular red hair color gene variants display significantly more freckles as they experience more waterside vacations.
According to Box, the results of this study start to identify specific behaviors that can be changed in children who are at high risk for melanoma in later life.
The study was conducted by the Colorado Kids Sun Care Program research team and was supported by grants from the National Institutes of Health. Box declares no conflicts of interest.