Melanin density and melanin type predict melanocytic naevi in 19-20 year olds of northern European ancestry

Recent advances in estimating the density of cutaneous melanin by spectroph otometry and the concentration of the two types of melanin (eumelanin and p haeomelanin) in hair offer the potential to define the risk of skin cancer in individuals more accurately. The presence of common melanocytic naevi on the arm is associated with an increased risk of melanoma, and in this stud y the associations of arm naevi with melanin density at the upper inner arm and with melanin type in hair samples were examined in a representative sa mple (n = 267) of 19 - 20 year olds of northern European ancestry. Particul arly in men, the association with naevus count was stronger for cutaneous m elanin density than for follicular melanin type. Adjusted for recreational sun exposure, the rank correlation coefficients were r = -0.25, 0.12 and 0. 01 for men, and r = -0.17, -0.12 and 0.14 for women, for cutaneous melanin, hair eumelanin and hair phaeomelanin, respectively. The associations with less objective markers of phenotype (hair colour, eye colour, nurse-assesse d skin colour, and self-reported skin reaction to unaccustomed sun) were we aker. These findings provide important new information that human susceptib ility to mutations of melanocytes can be estimated by objective biological measures. The next step is to determine whether these measures also predict the risk of melanoma. (C) 2000 Lippincott Williams & Wilkins.