Melanin Based Classification of Skin Types and Their Susceptibility to UV-Induced Cancer

One of the characteristics that easily distinguish every human being is their skin complexion. The primary pigment that brings about this distinction is melanin. And just like most other physical characteristics, the degree of pigmentation is a genetically inherited factor. As is explained by the gradation of colours from very light to dark brown, it is understood that skin colour is not governed by one specific gene, rather it is a polygenic trait. Skin colour is also influenced to some extent by the environment as well, for example, sun exposure. That is to say, while genetic expression decides the basal level of melanin synthesis, exposure to ultraviolet radiation acts as a fine tuner and upregulates or downregulates this synthesis and distribution. It is known with some clarity that apart from imparting pigment to the skin, melanin also plays a photoprotective role by preventing the cellular and molecular damage caused due to UV radiations. However, lately it has been observed that melanin also has deleterious effects that arise due to its photolabile nature. This chapter focuses on the ethnic classifications of skin types based on the melanin synthesis and susceptibility of these skin types to UV-induced cancer. Further it elaborates on the genetic correlates of melanin synthesis and distribution. The chapter concludes with the molecular mechanisms that underlie both the protective and the deleterious effects of melanin.