leucismi

Leucismo, in plural leucismi in some languages, is a genetic or developmental condition characterized by a partial loss of pigmentation in an animal. It results in white, pale, or patchy coloration of skin, scales, fur, or feathers while typically preserving normal eye color. Leucism differs from albinismo: albinism is a systemic absence of melanin that often affects the eyes, skin, and hair, whereas leucism may spare the eyes and involve only certain pigment cells or regions.

Causes and mechanisms include defects in the migration, proliferation, or survival of pigment cells derived from the neural crest, or mutations in genes regulating pigment production. Leucism can be inherited in various modes or occur sporadically through somatic mosaicism or chimerism. It is not a disease and does not imply illness per se.

Occurrence has been reported across many animal groups, including birds, mammals, reptiles, amphibians, and fish. Leucistic individuals are rare but notable in wild populations and captivity. Their coloration can affect camouflage and behavior, sometimes increasing predation risk or altering social interactions, though many leucistic animals lead normal lifespans and reproduce.

Diagnosis and terminology: leucism is distinguished from albinism by the usually preserved eye color and localized or partial loss of pigmentation. In practice, identification relies on phenotype and, when possible, genetic analysis. The term is used in several languages with similar meanings.