Difference between Codominance and Multiple Alleles

[LetsGo2DSchool]

My understanding is Multiple Alleles is a form of Codominance with the difference being that Codominance only deals with two alleles whereas Multiple Alleles deals with three or more alleles (such as A, B, AB, O blood). Is this correct?

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[PooyaH]

I would say for simplicity yes, you're right. But in the real world many traits have more than 2 or 3 alleles of different genes affecting a trait, which falls under polygenetic traits or multifactorial traits.

 

[Troyvdg]

My understanding is Multiple Alleles is a form of Codominance with the difference being that Codominance only deals with two alleles whereas Multiple Alleles deals with three or more alleles (such as A, B, AB, O blood). Is this correct?

your example of blood antigens is an example of multiple alleles that happen to be codominant, but not all multiple allele traits are codominant.

hair color for instance, you could have multiple alleles meaning red, brown, black, blond, but they aren't necessarily codminant