When a gene prevents the expression of another non allelic gene then it is known as epistatic gene and this phenomenon is known as Epistatis ...

And the expression of gene which is suppressed by epistatic gene is called hypostatic gene !!!!

Epistasis is a type of gene interaction in which an allele at one locus affects the expression of alleles at another locus. In this type of interaction, the allele at one locus is said to be epistatic to the allele at the other locus, which is said to be hypostatic. Epistasis is a form of gene interaction that is different from dominance, where one allele masks the expression of another allele at the same locus.

Epistasis can be of two types, recessive and dominant. In recessive epistasis, the presence of two recessive alleles at one locus prevents the expression of alleles at another locus. In dominant epistasis, the presence of one dominant allele at one locus prevents the expression of alleles at another locus.

The interaction between non-allelic genes in which an allele at one locus prevents the expression of an allele at another locus, but not vice versa, is called epistasis. This is an example of dominant epistasis, where the presence of one dominant allele at one locus prevents the expression of alleles at another locus.

This type of interaction can be illustrated by the coat color of Labrador retrievers. The gene for coat color in Labrador retrievers has two alleles, B (black) and b (brown). Another gene, E, controls the expression of the coat color gene. The E gene has two alleles, E (expressed) and e (not expressed). In this case, the E gene is epistatic to the coat color gene. If a Labrador retriever has at least one dominant E allele, the coat color gene is not expressed, and the dog will be yellow. If a Labrador retriever has two recessive e alleles, the coat color gene will be expressed, and the dog's coat color will be either black or brown, depending on the alleles at the coat color gene locus.

In summary, epistasis is a type of gene interaction in which an allele at one locus affects the expression of alleles at another locus. Dominant epistasis is a type of epistasis in which the presence of one dominant allele at one locus prevents the expression of alleles at another locus.