Mighty_Girl, the condition is possible (although rare in humans, but common in some animals). The usual term for having abnormally high levels of pigmentation is melanistic, although I may have misspelled it.
My question was about hiper-pigmentation.
Nope, spelled correctly. I’ve got several cornsnakes. Two of them are amelanistic, bright orange and yellow and white without the melanin that normally drabs the colors out. There are not to my knowledge true melanistic cornsnakes, though there are anerythristics- ones that only express the melanin pigmentation. I’ve got one of those too, she’s bright silver and black. A friend of mine has a melanistic death adder which is one creepy looking bastard. The snake that is, not my friend.
Peace,
~mixie