Leucism is a condition in animals characterized by reduced pigmentation. Unlike albinism, it is caused by a reduction in all types of skin pigment, not just melanin. Leucism (occasionally spelled leukism) is a general term for the phenotype resulting from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair, or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or patches of body surface (if only a subset are defective) having a lack of cells capable of making pigment.