What is a non-allelic interaction

What is a non-allelic gene?

I understand that a non-allelic gene is one that affects someone else's traits, but is not as typically dominant / recessive. If i correct lie , this is the same as Epistasis - which means that one gene changes the expression of another. There are epistatic genes for the horse's coat color. One gene is the coat color itself (horses can have either brown or red color balls in these areas), the second gene is for a protein with which the coat color gene can be expressed. For example, a horse has two brown alleles at the coat color location. It also has a wild type gene in the second (modifier) ​​position. With this modifier, the color brown can be expressed and the horse is brown. B / B, wt / wt -> brown If the horse has the two brown alleles but a mutated allele at the modifier position, the coat color is not expressed and the horse is white. B / B, mt / mt -> white

Because the modifier alleles are separate genes from the coat color alleles, the two are not allelic - yet both affect the same trait in some way.

I hope it helps.


+1 This is also my understanding of Terdon's link. However, I would argue that the name non-allelic gene is very poorly chosen. In theory, there could not be a single gene that does not affect the phenotypic expression of other genes. And of course, a non-allelic gene can only be a non-allelic gene if it is polymorphic (and has multiple alleles)!