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LWO Article, is this out-dated?

Here is an article we have to read for Advanced Breeding: "Incidence of the endothelin receptor B mutation that causes lethal white foal syndrome in white-patterned horses." Elizabeth M. Santschi, DVM; Paul D. Vrotsos, BS; Amanda K. Purdy, BS; James R. Mickelson, PhD AJVR Vol 62, No. 1, January 2001 Is this article supportive of Frame and LWO being the same thing and frame being masked by other genes like sabino, splash, etc? I have a quiz over this on friday and I really need to see if this is supportive of the above said statement.

horsegen Wed, 04/08/2009 - 14:38

It's not outdated per se...this is the paper that your awful professor uses as evidence that frame and LWO are two different things. (But she shouldn't.) Basically, the researchers looked at a bunch of horses with white patterns...some were tobiano, some frame, some splash, some sabino...and then tested them for LWO. They report the incidence of the LWO mutation in each of these white patterns. The point of the paper was really to show that even if you don't have a phenotypically "frame" animal, LWO can be present. Those of us familiar with LWO would not be surprised--we know that frame can hide within other white patterns, so certainly a horse that is phenotypically tobiano can also carry LWO and that's why we all should be testing our horses. But your professor uses it to show that if a horse that's not frame (like a tobiano) can carry LWO, then frame and LWO must be two separate things.

(If this is the case, then technically we should also find very obvious frame horses that do NOT carry LWO, but we don't.)