What does pleiotropy refer to in genetics?

Pleiotropy is a genetic phenomenon where a single gene has the ability to influence multiple, seemingly unrelated traits. This occurs because the gene in question may be involved in various biological pathways or physiological functions, leading to diverse effects on the organism. For instance, a mutation in a pleiotropic gene may affect traits like pigmentation, growth rate, and disease susceptibility all at once.

In contrast, the other options describe different genetic concepts. The first option pertains to polygenic inheritance, where multiple genes contribute to a single trait, such as height or skin color. The third option discusses the interactions between dominant and recessive alleles but does not address the broader influence of a single gene on multiple traits. Lastly, non-Mendelian inheritance patterns encompass various inheritance mechanisms that do not follow the classic Mendelian principles, but again do not specifically define pleiotropy.