Epistasis describes a condition whereby one gene controls the expression of another gene

In mice, the expression of a specific fur colour by one gene is dependent upon the production of hair pigment by another gene

  • Black fur (B) is dominant to brown fur (b), but in the absence of hair pigment (cc) mice will appear albino

In humans, the gene for baldness supersedes genes for hair colour and hence is epistatic in nature

Epistasis – Mouse Coat Colour