Primer in Genetics and Genomics, Article 7Multifactorial Concepts: Gene-Gene Interactions

Most common disorders affecting human health are not attributable to simple Mendelian (single-gene) inheritance patterns. Rather, the risk of developing a complex disease is often the result of interactions across genes, whereby one gene modifies the phenotype of another gene. These types of interactions can occur between two or more genes and are referred to as epistasis. There are five major types of epistatic interactions, but in human genetics, additive epistasis is most often discussed and includes both positive and negative subtypes. Detecting epistatic interactions can be quite difficult because seemingly unrelated genes can interact with and influence each other. As a result of this complexity, statistical geneticists are constantly developing new methods to enhance detection, but there are disadvantages to each proposed method. In this article, we explore the concept of epistasis, discuss different types of epistatic interactions, and provide a brief introduction to statistical methods researchers use to uncover sets of epistatic interactions. Then, we consider Alzheimer's disease as an exemplar for a disease with epistatic effects. Finally, we provide helpful resources, where nurses can learn more about epistasis in order to incorporate these methods into their own program of research.