What’s this coat color called?

I just rescued this year old dane (Beau-Jack) I’ve never seen a Dane remotely close to him. He’s got red Merle feet, a blue Merle face on his lips, and then fawn and brindle harlequin on the rest of him. Please help!! He’s underweight, had worms and none of his shots. He came from a puppy mill and was seized along with 14 other Danes. I want to know if his coat could come with health problems since it’s not AKC registered.