technically any pigmentation altering effect could be considered a defect, including flames. Defect is an opinionated term, it depends on what you personally consider a defect. I consider anything that would majorly hinder survival in the wild to be a defect. albinism, pied, and leucistic are examples of this. Hypo could also be in there but it can also be a positive attribute, it actually depends on how light the animal is and how that affects it's camoflage in the environment. Same thing with melanism and anerythristic. In some pupulations, snakes with these traits thrive, simply because their habitat allows them to.