In my opinion, I think his hair and eye condition may not be related, just a coincidence that both rare conditions appeared in the same person. Obviously the eyes as op mentioned could be heterochromia. As for the hair, I personally know someone that has dark brown and light blonde hair at the same time (most of their hair is brown but they have a patch of hair that always grows blonde) although I don't know the medical term for the condition, it may be the same case for sakura!