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Hypothetically Dominate White

Jackie May 15, 2012 May 15, 2012

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Hypothetically, is it at all possible for the SAME KIT mutation happen in unrelated horses? In each of the known mutations the DNA changes in a different way, but what's to say it can't randomly mutate the same way again in a different horse. I'm sure it would be very unlikely, but with all the Dominate White horses popping up, won't eventually the KIT run out out of different ways to mutate? I don't know if it's happened in mice, but with mice having a lot more known mutations, it would be easier to discover. This is just a random thought I had.

CMhorses Wed, 05/16/2012 - 14:10

I well if it is a matter of proteins changing, which from my understanding of how the mutations work it is, and we have already seen two different mutations on the same exon but they swapped out different proteins, then it would be entirely possible to see the same mutation happen again. Also wasn't this what happened with Catch a Bird? classic roan mutation happened again at random.

Jackie Wed, 05/16/2012 - 22:05

There are some different characteristics between the different splash mutations though. It seem that one dose of Splash 1 and 2 show more white than Splash 1 at it's heterozygous form. Has anyone seen the picture of the all white horse that is homozygous for splash 1 and heterozygous for Splash 2, and then the all white horse that is only heterozygous for splash 1 but also had splash 3. It seems when mixed together they act different.

Threnody Thu, 05/17/2012 - 00:40

Hence [u]similar[/u] phenotype. There are other genes and patterns boosting and suppressing the splash mutations as well, so that needs to be taken into account. Since SW2 is a recent mutation the genes of the one family line are heavily influencing it's expression in the tested horses we have seen. And there are only 2 identified SW3 horses so we severely lack enough info to know how it expresses on average. Overall their expression is similar to each other and inherit the same which is why they are all classified as Splash.

As far as CAB's roan it is different than the expression of the classic roan common in stock horses. It causes lots of white in the tail head and more roaning and ribbing around the flanks. It visually mimics Roan and Rabicano combined. Brabants likely have a different roan mutation as well that is noted for often causing mane frosting. Similar expression all classified as roan, but with separate mutations causing them.

Most mutations we see cause things to malfunction or turn off. So there are multiple ways of messing up the code to cause the same parts to not work as they normally would. In this case melanocyte migration is interrupted causing unpigmented areas on the coat.

A similar mutation can happen and probably will as far as DW is concerned (since it loves to pop up). It would be interesting to see if identical mutations do happen. If a test becomes commercially available for two identically caused mutations from different lines I wonder if researchers will decide to detect the direct mutation as well as close markers to differentiate them from each other.