Weird question about Bend Or spots

Anyone know what causes them? Are they related to the agouti gene?

My mare is a flaxen chestnut out of a chestnut mare and a palomino stallion, neither of them have bend or spots. I can't remember what colors are further back in the bloodline, but I suppose I could look it up...

Anyway, just curious.

Skips Miss Magnolia Quarter Horse

Her sire's dam was a buckskin, there were a few buckskins on that side, and one or two buckskins on her dam's side, but *mostly* chestnuts and a few palominos.

I have a sooty chestnut with a couple of Bend or sports.
Couldn't say if it is related to the agouti gene though.

It is not known what causes bend or spots to appear. It is a genetic color oddity at this point in time.

^^This.

My best, semi-educated guess though? It's likely a concentration of the sooty coloring, similar to the way that a blood mark is a concentration of fleabites on a gray horse.

I was trying to find some old pictures of her for comparison, but of course I couldn't. :/ When she was younger she did not have any spots at all. She had one Bend Or spot when she was 5. Now she has too many to count (and areas where so many have blended together and made a huge spot), and her hind legs are darkening, as well. She also has started getting white hairs interspersed with the chestnut... though definitely not evenly, so I wouldn't necessarily call it "roaning". And some white patches that aren't scars. She's a weirdo. :P

Could it be caused maybe by genetic DNA? Like something similar to chimerism?

My barn owners QH stud, Red, has them on his chest . All we know is that it's genes transferring from the TB horse Bend Or . Kinda cool though !
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It's not actually genetically related to Bend Or. He is just the one they are named after. Bend or spots can appear on any breed of horse, on pretty much any base colour. I have seen them be called grease spots, smut marks, and shadow spots.

As far as what is causing it, at the end of the day there is something genetic going on, probably something to do with sooty to be honest.

Just like NdAppy said, we really don't know why they get them, but I think their kinda cute haha. My 23yr old Thoroughbred has one right on his butt! >.<