The Effect of Sun Exposure in Determining Nevus Density in UK Adolescent Twins

• Published in: Journal of investigative dermatology Vol. 124; no. 1; pp. 56 - 62
• Main Authors: Wachsmuth, Rachel C., Turner, Faye, Barrett, Jennifer H., Gaut, Rupert, Randerson-Moor, Juliette A., Timothy Bishop, D., Newton Bishop, Julia A.
• Format: Journal Article
• Language: English
• Published: Danvers, MA Elsevier Inc 01-01-2005; Nature Publishing; Elsevier Limited
• Subjects: Adolescent; Biological and medical sciences; Child; Climate; Dermatology; Environmental Exposure; Female; Holidays; Humans; Male; Medical sciences; melanoma risk; nevi; Nevus - epidemiology; Nevus - genetics; Risk Factors; sun exposure; sun protection; Sunlight - adverse effects; Sunscreening Agents - administration & dosage; Tumors of the skin and soft tissue. Premalignant lesions; twin study; United Kingdom - epidemiology; United Kingdom; Europe; nevi; sun exposure; melanoma risk; twin study; sun protection; Human; Skin disease; Dermatology; Sun protection; Nevus; Malignant tumor; Density; Twin; Adolescent; Risk factor; Malignant melanoma; melanoma risk/nevi/sun exposure/sun protection/twin study; Solar radiation
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1111/j.0022-202X.2004.23548.x

We report a study of 221 teenage twin pairs to examine the genetic and environmental determinants of nevi representing the most potent phenotypic risk factor for melanoma. Our published heritability analysis estimated that nevi are mainly genetically determined. In this paper we examine the role of sun exposure. We report a correlation between nevus density and sun exposure, particularly that acquired in hotter countries than in the UK (mean nevus density 41 per m2 in those in the highest quartile of exposure vs 24 per m2 in those with no exposure, p<0.0001). We were not able to demonstrate a protective effect for either sun protection cream or shirt wearing. By including phenotypic variables and reported sun exposure into the heritability analysis, we conclude that 66% of the total variance of nevus count is attributable to genetic effects: 7% associated to eye color, 6% to hair color, and 1% to reported skin type, which leaves 52% as to yet unidentified genetic factors. Of the 25% of variation attributable to environmental influences, one-third is estimated to be because of sun exposure on hot holidays.