ABSTRACT
This chapter explains how an evolutionary perspective can help illuminate the genetic influences on complex disease incidence or prevalence. To reiterate, simple genetic diseases are almost always rare and are generally caused by a single high-penetrance disease allele within any particular family. Complex genetic diseases are those where a single disease allele (heterozygous or homozygous) is not sufficient to cause the disease; these diseases may be common in the population. The chapter provides an overview of how genetic factors in complex disease are discovered, and how evolutionary information can help to investigate the genetics of complex disease. It also provides several key examples of how the allelic architecture or allelic spectrum of a disease is influenced by evolution, with implications for understanding how the disease occurs and potential for treatment. The chapter discusses the importance of evolutionary information for medical treatments, particularly in the use of drugs to treat disease.
