Horse Color Genetics: Appaloosa Pattern Inheritance

Going back to the question that started it all, and what I determined. Can my solid black horse Chocolate with appaloosa breeding produce an appaloosa foal when bred to another solid horse?

The answer is no. Not to another solid horse, and I'll explain why.

The LP gene needs the master switch turned on. Without the master switch, none of the pattern genes work. BUT....that does not mean that Chocolate does not have pattern genes.

Both of Chocolate's parents were blanket appaloosas. But both were heterozygous for LP, and Chocolate inherited both of the recessive genes. How do pattern genes work?

You need to imagine each LP allelle seperately. Linked to each allelle are two different pattern gene options. Imagine the bunkbed, back from the KIT gene post. These mini-patterns that are linked to each main LP allelle can be either turned on or off, even if both of the main LP genes are recessive. Sort of like how a pillow and a blanket could be in the bunkbed whether someone is using them or not. I picture it like this:

LP patn/patn1     LP patn/patn1

The above shows each LP allelle seperately, with both pattern genes turned off. The first one is for leopard, the second is for blanket.

So that means that Chocolate, even though she is solid, could carry pattern genes, but the master switch is turned off. How does this translate to breeding?

Most appaloosa's carry pattern genes, so not having a pattern gene is not really a big deal. If Chocolate didn't have any pattern genes, but if I bred her to a homozygous appaloosa, then she would still probably throw a colorful foal. That is because any pattern genes the foal needed would come from the father.

This is not always the case, but I really would like to know how any genes Chocolate has could effect what LP pattern the foal could have. The stallion that I'm looking at is this guy:

He is homozygous LP, so the foal would certainly be heterozygous LP. But, within the heterozygous range, there are three pattern options: leopard, blanket, or varnish roan.

I would be so disappointed if it came out varnish roan, but because I've seen a lot of this stallion's offspring, and of the two foals Chocolate has had are super colorful, I am fairly certain that there is no chance the foal would not get no pattern genes. No pattern genes equals varnish roan, FYI.

Now, the question I am dying to know: which of the two remaining patterns is most probable?

The frustrating answer? There is no way to know. The information I want doesn't exist. Scientists are trying really hard to understand how appaloosa pattern inheritance works, but it is really hard to trace. My information that I wrote about above could be proven completely wrong in 10 years.

As a side note, one of Chocolate's foals was from this same stallion, JKB Quick Draw McGraw. The filly was a gorgeous black leopard. So I know that that is very likely to happen again. This is not the exact filly, but it did look a lot like this: