#ticked

Firestar - Black ticked tabby with white

I use agouti as a collective term for all tabbies (and i assume you do as the most stripeless ticked tabby), and i don't really try to differentiate between ticked tabbies any further, exactly because of things like what you are talking about. Getting all stripes off a ticked tabby is probably very challenging and requires some modifiers and not a clear yes-no situation. However i think i'd indeed guess homozygous tkcked, but i don't have much experience with ticked.

FIRESTAR

“Loyalty is what matters, and that exists now, not in the past.”

[Ginger ticked Abyssinian mix with medium white spotting and green eyes]

Orimgest dude of all time

Redesigned my Firestar (x2), and I’m SO glad that I did, cause look!! He’s so pretty! Lovely lad!

Yep, solid is epistatic over all tabby pattern genes, meaning it overrides all of them. The other genes strictly determine what the pattern is, but the Agouti gene determines whether the pattern will actually show.

The solid mutation is a nearly complete loss-of-function mutation. Usually, the Agouti protein regulates "switching" from black to red pigment at certain points along the hair shaft, down-regulating eumelanin production whenever it is active. The solid mutation isn't quite completely useless - there is still faint banding which is what allows you to see "ghost markings" in some cases. But the banding is between full eumelanin production and slightly less eumelanin production, so the cat isn't be a proper tabby.

Red cats have very little eumelanin in the coat. The causal gene for it hasn't been identified, but since they can have little specks of black pigment, I would guess it's something suppressing eumelanin production, not making them unable to make it. Regardless, that means that Agouti mutations don't effect them. Their patterns are from other yet to be identified proteins which must work in concert with Agouti.