Codominance vs. Incomplete Dominance Semantics (Question about AAMC 7)

[regeneration]

Advertisement - Members don't see this ad

#128, a discrete: Horses can have a red coat or a white coat if they are homozygous for those alleles. If they are heterozygotes, they are roan in color.

The question stem/answer refers to this as codominance. Isn't this considered incomplete-dominance, since both alleles are being expressed to create a combined phenotype? If it were codominance, as in bloodtypes, we would expect a white and red spotted horse, no?
http://en.wikipedia.org/wiki/Dominance_(genetics)#Incomplete_and_semi-dominance

 

[MedPR]

#128, a discrete: Horses can have a red coat or a white coat if they are homozygous for those alleles. If they are heterozygotes, they are roan in color.

The question stem/answer refers to this as codominance. Isn't this considered incomplete-dominance, since both alleles are being expressed to create a combined phenotype? If it were codominance, as in bloodtypes, we would expect a white and red spotted horse, no?
http://en.wikipedia.org/wiki/Dominance_(genetics)#Incomplete_and_semi-dominance

Incomplete dominance would result in a pink horse. Roan isn't actually a color. It's the term used when there are even amount of colored hairs as white hairs. A single hair isn't a combination of white and color like it would be in incomplete dominance.

http://en.wikipedia.org/wiki/Roan_(color)

 

[regeneration]

Incomplete dominance would result in a pink horse. Roan isn't actually a color. It's the term used when there are even amount of colored hairs as white hairs. A single hair isn't a combination of white and color like it would be in incomplete dominance.

http://en.wikipedia.org/wiki/Roan_(color)

*facepalm*. Thanks