Leucism

Source: Wikipedia, the free encyclopedia.
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]
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.

Leucism (/ˈluːsɪzəm, -kɪz-/)[2][3][4] is a wide variety of conditions that result in 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, Chédiak–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]

Details

(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

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

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.

Notable examples

Genetics

EDNRB.[13]

Etymology

The terms leucistic and leucism are derived from the stem leuc- + -ism, from Latin leuco- in turn derived from Greek leukos meaning white.

Gallery

See also

References

  1. PMID 24045858
    .
  2. Oxford Dictionaries. Oxford University Press. Archived from the original
    on August 10, 2012. Retrieved January 9, 2016.
  3. ^ Merriam-Webster, Merriam-Webster's Unabridged Dictionary, Merriam-Webster, archived from the original on 2020-05-25, retrieved 2015-11-12.
  4. ^ a b "leucism". The American Heritage Dictionary of the English Language (5th ed.). HarperCollins.
  5. ^ "Depigmentation of Skin: Symptoms, Signs, Causes & Treatment". MedicineNet. Retrieved 2020-06-23.
  6. ^ chemport.cas.org https://chemport.cas.org/cgi-bin/sdcgi?APP=ftslink&action=reflink&origin=npg&version=1.0&coi=1:CAS:528:DC%252BC3sXotlGksbg%253D&md5=1ee737efa06deefbbb993e3412a921a0. Retrieved 2020-06-23. {{cite web}}: Missing or empty |title= (help)
  7. ^ White crows at Cornell University.
  8. ^ Piebald ball pythons at Constrictors.com (archived 9 October 2006, from the original, accessed 18–22 July 2006).
  9. ^ "Oculocutaneous Albinism". NORD (National Organization for Rare Disorders). Retrieved 2020-06-23.
  10. ABC News Online
    , 2023-11-03
  11. ^ Coat color, dominant white Archived 2009-01-30 at the Wayback Machine at Online Mendelian Inheritance in Animals.
  12. ^ 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.
  13. ^ 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

  • Media related to Leucism at Wikimedia Commons
Retrieved from "https://en.wikipedia.org/w/index.php?title=Leucism&oldid=1209722520"