Question

What causes epistasis?

Answer 1

Genetics includes a phenomenon known as epistasis, in which the impact of a gene mutation is determined by the absence or presence of mutations in one or more other genes known as modifier genes. As a result, epistatic mutations have different effects when they occur alone than when they occur together. The term "epistasis" is used to describe how the effect of a gene variant is masked by other genes.

Complete answer:
Typically, epistasis aids in the description of a variety of phenomena such as functional interaction between genes, statistical deviation from additive gene action, and genetic outcome of mutations acting in the same genetic pathway.

One of the more common applications of epistasis analysis is the ordering of genes in a developmental and metabolic pathway. With the introduction of high-throughput genetic screens, such approaches have recently become more systematic, particularly in yeasts. Such surveys show that gene interactions are common, and their use aids in understanding the structure of the complex genetic networks.

Epistasis is common in human genetic diseases, but there are some examples where the usefulness of a specific interaction has been demonstrated. Epistasis emerges as a natural repercussion of the evolutionary process, as all resultant changes are based on previously occurring genetic alterations.

Thus, Epistasis is a natural consequence of the evolutionary process that is primarily caused by a type of interaction between the same genes.

Note: Duplicate epistasis is based on the presence of two loci. When a recessive allele conceals the expression of dominant alleles at two loci, it is called duplicate recessive epistasis. This is also known as a complementary gene action because both genes are required for an accurate phenotype to be available. When there is a dominant, epistasis is said to be duplicated gene action or dominant allele concealing the expression of recessive alleles at two loci.