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Kit is a gene that controls important physiological functions and mutations that break the gene significantly cause white markings of various kinds. Tobiano and Roan are two that are not lethal when homozygous, and they can be combined with any of the other Kit mutations without harm. The mutations that cause the many forms of dominant white are always homozygous lethal and lethal in combination. There are four Dominant White mutations in the game, each with its own recognizable pattern. (There are more than 20 of these in real life, and new ones occasionally appear spontaneously.) Sabino is the other set of mutations that cause white spotting. They can be combined with each other without harm. Heterozygous Sabino causes minimal to moderate markings. Homozygous Sabino causes extensive markings. There are three Sabino mutations in the game. Sabino 1 and Sabino 2 are lethal when combined with White 1 and White 2. They can be safely combined with White 3 and White 4. Sabino 3 can be safely combined with any White.

Pax3 is the gene that contains the mutation causing Splash 2. Splash 1 and 3 are on the MITF gene (which appears as Sp/Sps in the game gene reading). Splash 2 and 3 are lethal when combined.

Kit and Pax3 are the technical names for the genes. In common use, people tend to use the generic name for the phenotype--roan, dominant white, splash, etc. Ammit is a genetics guru, so she uses the technical terminology especially when the genetic situation is complex. So, it keeps the genetic code simpler to put all the Kit mutations together in one place, rather than having a notation for roan, another for tobiano, another for each of the whites and so forth. It also makes it clearer when one common name has been discovered to apply to mutations of more than one gene, like the splashes. Pax3 was added to the game list very recently.