Descriptions of coloration mutations:
Albinism is a congenital disorder in people and a hereditary condition in animals characterized by the complete or partial absence of pigment in the skin, hair/feathers, and eyes due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. An animal wth complete absence of melanin is called an albino and those with diminished amounts are called leucistic or albinoid. Albinism os associated with a number of vision defects, makes for a susceptibility to sunburn and skin cancer, and in rare cases (in people) Chediak-Higashi syndrome. It also affects essential granules present in immune cells, leading to increased susceptibility to infection.
Amelanisim is a pigmentation abnormality charcterized by the lack of pigments called melanins, commonly associated with genetic loss of tyrosinase function. It can affect fish, amphibians, reptiles, birds and mammals (including people). Lutino cockatiels are amelanistic
Aeumelanism is a loss of MC1R function, a recessive trait, that has been observed in many species. In humans, resulting in red hair, blond hair and melanoma. Aeumelanic hair coats, associated with mutations of the MC1R gene, have also been identified in mice, cattle, dogs, and horses. These coat colors are called "yellow" in mice and dogs, "red" in cattle and chestnut in horses. The loss of eumelanin in the coat is, in these species, harmless.
Aphaeomelanism is an abnormal absence of phaeomelanin from the integumentary system. Loss of function of agouti signalling protein can permit unmediated eumelanin production, producing a uniformly black-to-brown coat color. This condition can be observed in dogs, cats, and horses. The appearance of mammals with recessive agouti mutations is typically dense black. Some agouti alleles in mice are associated with health defects, but this is not the case in dogs, cats, or horses.
Hypomelanism is a condition in which there is a partial lack of the melanin, thus, a reduced pigmentation. It is used to describe reptiles and amphibians. It means the melanin production is reduced, not necessarily absent.
Leucism is a condition in which there is partial loss of pigmentation in an animal resulting in white, pale, or patchy coloration of the skin, hair, feathers, scales or cuticle, but not the eyes. Unlike albinism, it is caused by a reduction in multiple types of pigment, not just melanin. It includes white peacocks and white lions.
Dilutes have melanocytes, but vary from darker colors due to the concentration or type of these pugment-producing cells, not their absence. Pigment dilution, sometimes referred to as hypomelanism, effects cremello horses and cats, as well as other animals.