Albinism (human) - Related Pigment Disorders

Related Pigment Disorders

In some animals, albinism-like conditions may affect other pigments or pigment-production mechanisms:

• "Whiteface," a condition that affects some parrot species, is caused by a lack of psittacins.
• Axanthism is a condition common in reptiles and amphibians, in which xanthophore metabolism is affected rather than synthesis of melanin, resulting in reduction or absence of red and yellow pteridine pigments.
• Leucism differs from albinism in that the melanin is, at least, partially absent but the eyes retain their usual color. Some leucistic animals are white or pale because of chromatophore (pigment cell) defects, and do not lack melanin.
• Melanism is the direct opposite of albinism. An unusually high level of melanin pigmentation (and sometimes absence of other types of pigment in species that have more than one) results in an appearance darker than non-melanistic specimens from the same genepool.

Plants that are pale due to a mutation that eliminates chlorophyll production are sometimes termed albinos, whereas plants that are pale from being in the dark are called etiolated. Albino redwoods are rare examples that may grow to substantial size as parasites.