Part One: The Base Colors [link] Part Two: The Cream Gene [link] Part Three: The Champagne Gene [link] Part Four: The Dun Gene [link] Part Five: The Silver Gene [link] Part Six: White Patterns [link]
Appy genes are pretty complicated and not entirely understood yet. The theory is that a horse first has to have the gene for Spotting (LP), and then on TOP of that have additional genetic coding (either an allele of the LP gene or another separate gene) for the particular pattern. There are a few sites out there covering Appaloosa genetics, but because of the lack of concrete info, I didn't put it on the reference
I taught myself for the most part, and had a lot of help from JNFerrigno who knows this stuff a lot better than I do. In terms of genetics, Appy patterns are the most complicated. Everything else is fairly straightforward lol