Originally Posted by Nokotaheaven
We had a sorrel QH with jaggety stockings and a jaggety sock, so now I wonder if he had anything else going on, like minimal sabino...
Most certainly. Any white that is not from scarring is caused by a specific gene, be it roan, pinto [of the various types], appaloosa, rabicano, or even stages of grey. A Gulastra Plume [white tail, particularly on a bay or black] is thought to be caused by sabino, though greys can appear to have the Plume at certain stages of greying.
Tobiano can be as minimal as a white coronet [there is a TO/TO (homozygous) Mini with just two small socks on the hind legs], frame as minimal as no signs at all [there is a Mini out there that is solid black except for two blue eyes, tested positive for frame, and several horses with "normal" white also tested positive]. Completely solid horses have had loud splashed white foals. The genes can hide!