What is the term for when a single gene produces multiple effects?

The correct term for when a single gene produces multiple effects is pleiotropy. This phenomenon occurs when one gene influences multiple, seemingly unrelated phenotypic traits. For example, a single gene that affects both pigmentation and fur texture in an animal illustrates pleiotropy, as the effects of that gene are seen in different characteristics rather than being confined to a single trait.

In contrast, polygenic inheritance refers to traits that are influenced by multiple genes, leading to a continuum of phenotypes, such as height or skin color in humans. Epistasis involves interactions between genes, where the expression of one gene can mask or modify the effect of another gene. Codominance describes a situation in genetics where both alleles contribute equally and visibly to the phenotype, such as in AB blood type, which is characterized by both A and B antigens being expressed simultaneously.

Understanding pleiotropy is essential in genetics because it highlights the complexity of gene interactions and the potential for a single genetic change to have widespread effects on an organism.