What is "paramutation"

n. (context genetics English) A mutation in which a heritable change in one allele is induced by another in the same locus

In epigenetics, a paramutation is an interaction between two alleles at a single locus, whereby one allele induces a heritable change in the other allele. The change may be in the pattern of DNA methylation or histone modifications. The allele inducing the change is said to be paramutagenic, while the allele that has been epigenetically altered is termed paramutable. A paramutagenic allele may have altered levels of gene expression, which may continue in offspring which inherit that allele, even though the paramutagenic allele may no longer be present. Through proper breeding, paramutation can result in sibling plants that have the same genetic sequence, but with drastically different phenotypes.

Though studied primarily in maize, paramutation has been described in a number of other systems, including animal systems like Drosophila melanogaster and mice. Despite its broad distribution, examples of this phenomenon are scarce and its mechanism is not fully understood.