Development of an integrated method of skin phenotype measurement using the melanins.

Different types of melanin pigments have recently been identified and recognized as critical determinants of the photosensitivity of individuals. Eumelanin, the black to brown melanin pigments, are believed to protect against ultraviolet-induced cell damage, while phaeomelanin, the reddish brown variant, is thought to be photosensitizing. The relative, qualitative and absolute amount of melanin production under stimulation of solar radiation is likely to be genetically determined. The hypothesis of this study is that determination of these values can help in identifying those people who are less protected. However, these techniques must be evaluated at a population level and against traditional epidemiological measures. We assessed the amount and type of melanin in 195 subjects in four centres across Europe, relating the results to epidemiological measures such as skin characteristics, history of sunburns and number of naevi. The most important finding was that eumelanin and phaeomelanin have very different distributions in the population, being associated with other phenotype characteristics with different patterns. The relationship between phaeomelanin and eumelanin is linearly inverse in the range from black to dark blonde hair colour, while it is weakly directly proportional in the range from dark blonde to light blonde, with people with red hair showing a peculiar pattern. Phaeomelanin rather than eumelanin seemed to be independent of other skin characteristics. The results show the feasibility of a further study with an appropriate case-control design and accurate determination of melanin.