White Patterns

[Argent II]

Reference, mostly.

Belgians, Caspians, and Turkmenes do not carry any white patterns,
Appaloosa is NOT found in Shetlands but was apparently found in the ancient Tarpan.
Tobiano, Overo, Splash, and Sabino are found in Shetlands and NABs (based on descendant breeds).
Dominant White is present in Arabians and many Arab-derived breeds. Some minimal expressions could potentially be added to Forest Horses.

[Kintara]

Overo, as in frame overo wasn't found in any UK based breeds as far as I know, including Shetlands. The American derivative breeds often do though

[equagga]

Actually, I'd bet that Belgians carry at least one white gene - W20, the most minimally expressed dominant white mutant. I don't know of any Belgians who have been tested for it but it's been found in other draft breeds, so it would make sense to give it to them. It's found in a LOT of breeds, though, including breeds that are considered solid-only, so if the game implements all the white mutants, this should be the easiest to find. It only adds white to the face and legs.
If a horse has other white patterns, W20 extends it. Ex: heterozygous tobianos usually do not have white faces, and may have nothing but socks and a splat on the shoulder, but when W20 is involved, they can have face markings and be louder.

One of the hurdles with implementing white is going to be how many lines of dominant white appeared in modern breed families. Take W5, for example. That mutation is so new we have pictures of the founders. I personally don't know how I'd work that into the game, other than to pick a breed ancestral to the TB and pretend it wasn't a lie!

[Alana]

Sabino is definitly present in Arabians

[Argent II]

Arabians are not sabino via SB1, but by some other gene as of yet unidentified.

[MysticalHaven]

Here is a link that explains all about genetics in Arabians https://www.arabianhorses.org/.content/ ... tterns.pdf
It has very interesting information.

[Kintara]

What they call sabino in arabians is likely mostly dominant white, spotted white, whatever it's called these days. It's the 'new' sabino anyway. Basically sabino as a term is now defunct except for sb1. After sb1 all 'sabino' type patterns are named as 'whites'. So yes Arabians have W3 and W20, but when found their other sabino type patterns will be called a W too, not named sb