- The interaction of genes that are not alleles, in particular the suppression of a gene by a different gene.
- E.g. windows peak:
- Allele results in a “V shaped” hair
- Another allele expressed results in baldness
- Therefore, if carrier of both, as the person is bald the allele for widow’s peak is unclear
Phenotypic ratios for Epistatic Genes
- Recessive Epistatic Alleles
- If the epistatic allele is recessive then 2 copies of it will mask the expression of the other gene
- Homozygous parent + homozygous parent = 9:3:4 phenotypic ratio
(dominant both: dominant epistatic/recessive: recessive epistatic (in F2))
- Dominant Epistatic Alleles
- If the epistatic allele is dominant then 1 copies of it will mask the expression of the other gene
- Homozygous parent + homozygous parent = 12:3:1 phenotypic ratio
(dominant epistatic: recessive epistatic, dominant other: recessive (in F2))