Understanding the genetic basis of pigmentation in human populations

        Pigmentation shows a tremendous amount of variation in human populations, most probably due to the action of natural selection. In spite of decades of study, there are many gaps in our knowledge of the genetic basis of normal pigmentation variation and the evolutionary history of the genes responsible for pigmentation. One of the main reasons for this lack of knowledge is the multifactorial nature of this trait. Although the last century has witnessed impressive advances in our understanding of simple mendelian traits and diseases, elucidating the genetic factors responsible for variation in complex traits remains a challenge. However, conditions are in place to begin to identify the ultimate genetic factors involved in pigmentation variation within and between populations. We have better technologies and a better knowledge of the pigmentary system than anytime in the past, and there is much that can be learned from a systematic study of pigmentation candidate genes in multiple population groups. Toronto is one of the most cosmopolitan cities in North America and it will be possible to sample a wide range of pigmentation phenotypes. A study of these characteristics will potentially clarify important questions regarding the evolution of pigmentary genes. What is important to know is both which genes are involved, and also when, how and why the diversity we observe today in this trait came to be.

Figure: Representation of a melanocyte indicating some important genes of the pigmentary system. See Parra 2007 for additional information.