Epicanthic fold

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Epicanthic fold
Epicanthic KR02.jpg
A South Korean person with the skin fold of the upper eyelid covering the inner angle of the eye[1]
Details
SynonymsEpicanthal fold, epicanthus, eye fold,[3] Mongolian fold,[4] palpebronasal fold[5]
Pronunciation/ɛpɪˌkænθɪk ˈfld/[1]
Identifiers
LatinPlica palpebronasalis[2]
TAA15.2.07.028
FMA59370
Anatomical terminology

The epicanthic fold is the skin fold of the upper eyelid, covering the inner corner (medial canthus) of the eye. Various factors influence whether epicanthic folds form, including ancestry, age, and certain medical conditions.

Factors[edit]

Geographic distribution[edit]

Epicanthic folds are more frequently seen in East Asians, Southeast Asians, Central Asians, North Asians, some South Asians, Polynesians, Micronesians, Indigenous Americans (as well as Mestizos), the Khoisan, Malagasy, occasionally Europeans (e.g., Scandinavians, English, Irish,[6] Hungarians, Russians, Poles, Lithuanians, Finns, Estonians and Samis),[7][8] and among Nilotes and Amazigh people.[9] The degree of development of the fold between individuals varies greatly and its presence or absence is often subjective, also its frequency varies clinally across Eurasia. Its use, therefore, as a phenotypic marker to define biological populations is debatable.[10]

Possible evolutionary function[edit]

The epicanthic fold is often associated with greater levels of fat deposition around the eyeball, a feature most accentuated in native North Siberian, Aleut and Inuit populations. The adipose tissue is thought to provide greater insulation for the eye and sinuses from the effects of cold, especially from freezing winds, and to represent an adaptation to cold climates. It has also been postulated that the fold itself might provide a level of protection from snow blindness. Though its appearance in peoples of Southeast Asia can be linked to possible descent from cold-adapted ancestors, its occurrence in various African peoples precludes a cold-adaptive explanation for it appearing in the latter groups. The epicanthic fold found in some African people has been tentatively linked to protection for the eye from the high levels of ultra-violet light found in desert and semi-desert areas.[11]

Age[edit]

Many fetuses lose their epicanthic folds after three to six months of gestation.[12] Epicanthic folds may be visible in the development stages of young children of any race, especially before the nose bridge fully develops.[13]

Medical conditions[edit]

The epicanthic fold is sometimes found as a congenital abnormality. Medical conditions that cause the nasal bridge not to mature and project are associated with epicanthic folds. About 60% of individuals with Down syndrome (also known as trisomy 21) have prominent epicanthic folds.[14][15] In 1862, John Langdon Down classified what is now called Down syndrome. He used the term mongoloid for the condition. This was derived from then-prevailing ethnic theory[16] and from his perception that children with Down syndrome shared physical facial similarities (epicanthic folds) with those of Blumenbach's Mongolian race. While the term "mongoloid" (also "mongol" or "mongoloid idiot") continued to be used until the early 1970s, it is now considered pejorative and inaccurate and is no longer in common use about medical conditions.[17]

In Zellweger syndrome, epicanthic folds are prominent.[18] Other examples are fetal alcohol syndrome, phenylketonuria, and Turner syndrome.[19]

See also[edit]

References[edit]

  1. ^ a b "epicanthic". Oxford Dictionaries. Oxford University Press. Retrieved 11 October 2012.
  2. ^ "AllRefer Health - Epicanthal Folds (Plica Palpebronasalis)". AllRefer.com. Archived from the original on 12 January 2010. Retrieved 2009-10-01.
  3. ^ "Eye fold".
  4. ^ Das, Ram Narayan (1997). Sterling Dictionary of Anthropology. Sterling.
  5. ^ "Palpebronasal Fold - Medical Dictionary Search". Stedman's Medical Dictionary. 2006. Retrieved 2009-10-01.
  6. ^ "Q&A". The New York Times. 1985-10-08. ISSN 0362-4331. Retrieved 2016-11-12.
  7. ^ "epicanthic fold (anatomy)". Encyclopædia Britannica. Retrieved 25 April 2014.
  8. ^ Montagu, A. (1989). Growing Young (2nd ed.). Granby, Mass: Bergin & Garvey. ISBN 0-89789-166-X.
  9. ^ "Mongolism in Sudanese children". Journal of Tropical Pediatrics. 8: 48–50. September 1962. doi:10.1093/oxfordjournals.tropej.a057626. PMID 13905256.
  10. ^ Lang, Berel (ed.) (2000) Race and Racism in Theory and Practice, Rowman & Littlefield, p. 10
  11. ^ Lang, Berel (ed.) (2000) Race and Racism in Theory and Practice, Rowman & Littlefield, pp. 10-11
  12. ^ Park JI (2000-01-01). "Modified Z-Epicanthoplasty in the Asian Eyelid". Archives of Facial Plastic Surgery. 2 (1): 43–47. doi:10.1001/archfaci.2.1.43. ISSN 1521-2491.
  13. ^ https://medlineplus.gov/ency/article/003030.htm U.S National Library of Medicine
  14. ^ Hammer, edited by Stephen J. McPhee, Gary D. (2010). "Pathophysiology of Selected Genetic Diseases". Pathophysiology of disease : an introduction to clinical medicine (6th ed.). New York: McGraw-Hill Medical. pp. Chapter 2. ISBN 978-0-07-162167-0.
  15. ^ Pham, V. (2010). COMMON OTOLARYNGOLOGICAL CONGENITAL ABNORMALITIES. UTMB, Dept. of Otolaryngology. [1]
  16. ^ Conor, WO (1999). "John Langdon Down: The Man and the Message". Down Syndrome Research and Practice. 6 (1): 19–24. doi:10.3104/perspectives.94.
  17. ^ Howard-Jones, Norman (1979). "On the diagnostic term "Down's disease"". Medical History. 23 (1): 102–04. doi:10.1017/s0025727300051048. PMC 1082401. PMID 153994.
  18. ^ Kalyanasundaram, S.; et al. (2010). "Peroxisomal Disorder-Unusual Presentation as Failure to Thrive in Early Infancy". Indian Journal of Pediatrics. 77 (10): 1151–1152. doi:10.1007/s12098-010-0199-6.
  19. ^ Kaneshiro, Neil K.; Zieve, David; Ogilvie, Isla. "Epicanthal folds". MedlinePlus.

External links[edit]