Quote Originally Posted by pankthesnake View Post
Dominant genes DO have a homo form, its just that its visually the same as the het form. The only difference between dominant and co-dom genes are the lack of a visually different super form with the dominant genes.
This. Heterozygous is one allele, homozygous is two alleles. Every gene of every creature can be one or the other. Really it's semantics, that dominant has no visible super (homozygous) form but has a visible het form, co-dom has a visible het form and a distinctively different super (homozygous) form, and recessive has only a visible Homozygous form (excluding red axanthics which is just more semantics).

Whether the homozygous form is visibly different from het, lethal, or has genetic problems doesn't change the fact that the allele has 2 mutations (homo) as opposed to one (het).