And that's exactly what play atrophy is. So a single gene or a pair of genes on a single locus affects many different types of phenotype characteristics, and this is known as plyotropy. Now, what about epistasis? Well, in many cases, a gene creates a protein that goes on to a second gene, and that protein affects the expression of that second gene. And this process can continue until some type of trait is actually expressed, and this is what we call epistasis. So in many cases, a gene at one locus produces a protein that goes on to a second locus and affects the expression of that gene at that second locus.