Leucistic white lions owe their colouring to a recessive allele. Note the eyes and lips remain the normal colour. Studies have shown that the reduced pigment comes from a mutation in the gene for tyrosinase, the same as causes Type I oculocutaneous albinism in humans.[1]
Leucism is often used to describe the phenotype that results 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 that can make pigment.
Since all pigment cell-types differentiate from the same multipotent precursor cell-type, leucism can cause the reduction in all types of pigment. This is in contrast to albinism, for which leucism is often mistaken. Albinism results in the reduction of melanin production only, though the melanocyte (or melanophore) is still present. Thus in species that have other pigment cell-types, for example xanthophores, albinos are not entirely white, but instead display a pale yellow color.
More common than a complete absence of pigment cells is localized or incomplete hypopigmentation, resulting in irregular patches of white on an animal that otherwise has normal coloring and patterning. This partial leucism is known as a "pied" or "piebald" effect; and the ratio of white to normal-colured skin can vary considerably not only between generations, but between different offspring from the same parents, and even between members of the same litter. This is notable in horses, cows, cats, dogs, the urban crow[7] and the ball python[8] but is also found in many other species.
Due to the lack of melanin production in both the retinal pigmented epithelium (RPE) and iris, those affected by albinism sometimes have pink pupil due to the underlying blood vessels showing through. However, this is not always the case and many albino animals do not have pink pupils.[9] The common belief that all albinos have pink pupils results in many albinos being incorrectly labeled as 'leucistic'. The neural crest disorders that cause leucism do not result in pink pupils and therefore most leucistic animals have normally colored eyes. This is because the melanocytes of the RPE do not derive from the neural crest. Instead, an out-pouching of the neural tube generates the optic cup that, in turn, forms the retina. As these cells are from an independent developmental origin, they are typically unaffected by the genetic cause of leucism.
^ at Atlas of Genetics and Cytogenetics in Oncology and Haematology (archived 26 December 2005, from the original, accessed 18–22 July 2006).
External links
Media related to Leucism at Wikimedia Commons
May 03, 2023
leucism, wide, variety, conditions, that, result, partial, loss, pigmentation, animal, causing, white, pale, patchy, coloration, skin, hair, feathers, scales, cuticles, eyes, occasionally, spelled, leukism, some, genetic, conditions, that, result, leucistic, a. Leucism ˈ l uː s ɪ z em k ɪ z 2 3 4 is a wide variety of conditions that result in the partial loss of pigmentation in an animal causing white pale or patchy coloration of the skin hair feathers scales or cuticles but not the eyes 4 It is occasionally spelled leukism Some genetic conditions that result in a leucistic appearance include piebaldism Waardenburg syndrome vitiligo Chediak Higashi syndrome flavism isabellinism xanthochromism axanthism amelanism and melanophilin mutations Pale patches of skin feathers or fur often referred to as depigmentation can also result from injury 5 Leucistic white lions owe their colouring to a recessive allele Note the eyes and lips remain the normal colour Studies have shown that the reduced pigment comes from a mutation in the gene for tyrosinase the same as causes Type I oculocutaneous albinism in humans 1 This white horse owes its coloring to a dominant allele dominant white A leucistic rock dove Both the eyes and legs are still of the normal colour Contents 1 Details 2 Genetics 3 Etymology 4 Gallery 5 See also 6 References 7 External linksDetails Edit source source source source source video A white tiger at Tobu Zoo in Saitama Japan This phenotype is due to a mutation in the same gene that results in Type IV Oculocutaneous albinism in humans 6 Leucism is often used to describe the phenotype that results 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 that can make pigment Since all pigment cell types differentiate from the same multipotent precursor cell type leucism can cause the reduction in all types of pigment This is in contrast to albinism for which leucism is often mistaken Albinism results in the reduction of melanin production only though the melanocyte or melanophore is still present Thus in species that have other pigment cell types for example xanthophores albinos are not entirely white but instead display a pale yellow color More common than a complete absence of pigment cells is localized or incomplete hypopigmentation resulting in irregular patches of white on an animal that otherwise has normal coloring and patterning This partial leucism is known as a pied or piebald effect and the ratio of white to normal colured skin can vary considerably not only between generations but between different offspring from the same parents and even between members of the same litter This is notable in horses cows cats dogs the urban crow 7 and the ball python 8 but is also found in many other species Due to the lack of melanin production in both the retinal pigmented epithelium RPE and iris those affected by albinism sometimes have pink pupil due to the underlying blood vessels showing through However this is not always the case and many albino animals do not have pink pupils 9 The common belief that all albinos have pink pupils results in many albinos being incorrectly labeled as leucistic The neural crest disorders that cause leucism do not result in pink pupils and therefore most leucistic animals have normally colored eyes This is because the melanocytes of the RPE do not derive from the neural crest Instead an out pouching of the neural tube generates the optic cup that in turn forms the retina As these cells are from an independent developmental origin they are typically unaffected by the genetic cause of leucism Genetics EditGenes that when mutated can cause leucism include c kit 10 mitf 11 and EDNRB 12 Etymology EditThe terms leucistic and leucism are derived from the stem leuc ism from Latin leuco in turn derived from Greek leukos meaning white Gallery Edit Leucistic Texas rat snake Elaphe obsoleta Leucistic common grackle Quiscalus quiscula Leucistic Indian peacock Pavo cristatus Leucistic American alligator Alligator mississippiensis Leucistic eastern gray squirrel Sciurus carolinensis See also EditAlbino and white squirrels Amelanism Dyschromia Erythrism Heterochromia iridum Albinism Melanism Piebaldism Vitiligo XanthochromismReferences Edit Cho Yun Sung Hu Li Hou Haolong Lee Hang Xu Jiaohui Kwon Soowhan Oh Sukhun Kim Hak Min Jho Sungwoong Kim Sangsoo Shin Young Ah 2013 09 17 The tiger genome and comparative analysis with lion and snow leopard genomes Nature Communications 4 1 2433 Bibcode 2013NatCo 4 2433C doi 10 1038 ncomms3433 ISSN 2041 1723 PMC 3778509 PMID 24045858 leucistic Oxford Dictionaries Oxford University Press Archived from the original on August 10 2012 Retrieved January 9 2016 Merriam Webster Merriam Webster s Unabridged Dictionary Merriam Webster a b leucism The American Heritage Dictionary of the English Language 5th ed HarperCollins Depigmentation of Skin Symptoms Signs Causes amp Treatment MedicineNet Retrieved 2020 06 23 chemport cas org https chemport cas org cgi bin sdcgi APP ftslink amp action reflink amp origin npg amp version 1 0 amp coi 1 CAS 528 DC 252BC3sXotlGksbg 253D amp md5 1ee737efa06deefbbb993e3412a921a0 Retrieved 2020 06 23 a href Template Cite web html title Template Cite web cite web a Missing or empty title help White crows at Cornell University Piebald ball pythons at Constrictors com archived 9 October 2006 from the original accessed 18 22 July 2006 Oculocutaneous Albinism NORD National Organization for Rare Disorders Retrieved 2020 06 23 Coat color dominant white Archived 2009 01 30 at the Wayback Machine at Online Mendelian Inheritance in Animals An L1 element intronic insertion in the black eyed white Mitf mi bw gene the loss of a single Mitf isoform responsible for the pigmentary defect and inner ear deafness at Human Molecular Genetics Waardenburg syndrome at Atlas of Genetics and Cytogenetics in Oncology and Haematology archived 26 December 2005 from the original accessed 18 22 July 2006 External links Edit Media related to Leucism at Wikimedia Commons Retrieved from https en wikipedia org w index php title Leucism amp oldid 1150532329, wikipedia, wiki, book, books, library,
