Dictionary:

epicanthic fold

  (ĕp'ĭ-kăn'thĭk)

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A fold of skin of the upper eyelid that partially covers the inner corner of the eye. Also called epicanthus.

In human anatomy, this is the fold of skin covering the inner corner (canthus) of the eye, normally from the top of the eye downward in a semilunar form. The epicanthic (or epicanthal) fold is a normal feature of fetuses of all races but is present in a pronounced form and in high concentrations in humans of certain geographic races and subraces. The epicanthic fold is sometimes referred to as the ‘Mongolian eye fold’, because of its high incidence in and historical association with the Mongoloid (Asian) geographic race. The presence or absence of the epicanthus, which helps produce in Asians a distinctive eye shape and facial appearance, has helped fuel controversies in physical anthropology and evolutionary theory, including historical attempts to establish racial hierarchies based on evolutionary fitness and disputes concerning the nature of evolutionary adaptation. In addition, epicanthic folds in individuals of groups without a high normal incidence of its presence is often phenotypic of genetic or congenital disorders. In some recent debates, the alleged absence of the fold in some depictions and descriptions of humans from Chinese and Indian history has led some Afrocentric historians to claim an African origin of at least some aspects of Indian and Shang dynasty Chinese culture.

In addition to Asians and eastern subarctic and arctic Eurasians, some native American peoples (especially those of Middle America and some populations in South American lowland areas), the Capoid local race of southern Africa, and some of the composite racial groups of Pacific island peoples have high incidence of developed epicanthic folds. The fold occurs less frequently in Southeast Asian populations and in North American Indian groups but occurs occasionally in some European groups, for example in some Scandinavians and Poles.

While epicanthic folds occur more frequently in Asiatic groups and those peoples genetically linked to Asia, its presence is not universal in these peoples and it occurs less frequently in other groups. The incidence of epicanthic folds varies widely among the nine major geographic races and their local races. Attempts to define racial groups by the presence or absence of such features, by phenotype, rather than by genotype and specific inherited traits, are historically problematic and scientifically unreliable. There is substantial variation in phenotype within geographic races and subraces produced by the gene flow inevitable in an aggressively mobile species such as our own, by environmental conditions, and simply by individual variation due to a number of causes, including genetic mutation and the ‘small-sample’ effects of isolated population groups. Modern genetics rejects the notion of a ‘pure’ race; while the historical origins of some geographic groups are obscure, contemporary racial groups are mixtures of the gene pools of many geographic races. Thus, the presence or absence of a developed epicanthic fold, while an indication of one of a number of genetic origins and an important diagnostic feature of certain genetic disorders, cannot bear the cultural freight often bequeathed to it by history, pseudo-science, and prejudice.

The association of the epicanthic fold with Mongolians and Asians more generally served to reinforce notions of racial and cultural supremacy in nineteenth and early-to-mid twentieth century European physical anthropology, physiognomy, and racial theory. Humans with the genetic anomaly now known as Down's syndrome, caused by having three copies (trisomy) of chromosome 21, have limited physical growth and mental retardation of varying severity, and an increased risk of other serious physical problems. Down's syndrome is one of the more common chromosomal defects, occurring on average in 1 in 900 live births. The Down's syndrome infant is quickly recognized by both facial and more general cranial characteristics, including a rounded head, short neck, thin and usually fine hair, flat nose, small mouth, and, especially, slanting eyes with pronounced epicanthic folds.

John Langdon Haydon Down first described this syndrome in 1866 and termed it ‘mongolism’ because of the eyefold and other facial features that Down believed linked the European children he observed to geographic races with a high incidence of such features, including the Asian geographic race (of which the Mongolian people constitute a local race). Down's report on this condition is an important example of the influence of cultural assumptions both on reading facial features and on the construction of anthropological theories designed to categorize and judge peoples: his comparison of European children born with a chromosomal disorder with the normal features of many Mongolians was both scientifically inaccurate as an analysis of the condition and a patronizing mischaracterization of Mongolians. Down argued that these children represented a degeneration of the superior (European) human type, stating that ‘A very large number of congenital idiots are typical Mongols.’ The racial theories used by Down and others have been decisively rejected by modern science, but it is only recently that the descriptions of Down's syndrome as ‘mongolism’ or ‘mongolian idiocy’ and persons with Down's syndrome as ‘mongols’ or ‘mongolian idiots’ have begun to fade from view.

In addition to Down's syndrome, epicanthic folds occur in other, less common genetic disorders, including Trigonocephaly ‘C’ syndrome and two types of ‘Blepharophimosis, Ptosis, Epicanthus Inversus Syndrome’ (BPES). In the latter condition, the epicanthic fold is inverted, extending from the lower eyelid up the side of the nose. Folds also occur in certain congenital conditions, including fetal alcohol syndrome. While the facial anomalies of infants with fetal alcohol syndrome are usually less pronounced than those of a Down's syndrome child, some of the same features occur, including a flat nose and nasal bridge, and developed epicanthic folds.

— Jeffrey H. Barker

A characteristic crease in the eyelid; seen in persons with Down syndrome.

A man from a mixed race background with an epicanthal fold.

Eye with epicanthal fold

An epicanthal fold, epicanthic fold, or epicanthus is a skin fold of the upper eyelid (from the nose to the inner side of the eyebrow) covering the inner corner (medial canthus) of the human eye. The presence of an epicanthal fold is present in people of East Asian and Southeast Asian descent, as well as other ethnic groups including some Native Americans and Africans. Epicanthal folds may also be seen in young children of any race before the bridge of the nose begins to elevate.

The term "epicanthal fold" refers to a visually categorized feature; however the underlying physiological reason and purpose for its presence in any given individual may be entirely different.

In children

All humans initially develop epicanthal folds in the womb. Some children lose them by birth, but epicanthal folds may also be seen in young children of any ethnicity before the bridge of the nose begins to elevate. They may persist where birth is pre-term, and sometimes also where the mother is alcoholic.

Pathological

In caucasoids the presence of the epicanthal fold can be a symptom of fetal alcohol syndrome, chromosomal disorders such as Down syndrome (Trisomy 21),^[1], Cri du Chat syndrome, or pre-term birth.

Inherited

There are numerous populations, across the world, that lack an epicanthic fold . However, the epicanthic fold is common in people of many, though not all groups of East Asian and Southeast Asian descent. It is found in significant numbers amongst Native Americans, the Khoisan of Southern Africa, many Central Asians and some people of Sami origin. It also present on people of Tibetan descent, especially Tibetans and North-East Burmese people. Due to classic genetics children of a parent with a pronounced epicanthal fold and one without an epicanthal fold will have varying degrees of epicanthal folds as a result.

In Asian ethnicities, the presence of an epicanthic fold is associated with a less prominent upper eyelid crease, commonly termed "single eyelids" as opposed to "double eyelids". The two features are distinct; a person may have both epicanthal fold and upper eyelid crease, one and not the other, or neither.

Surgical alteration

The procedure of reducing or removing epicanthal folds is epicanthoplasty. It is now an extremely rare procedure. Asian blepharoplasty, however, is a popular form of cosmetic surgery in East Asia.

See also

• Human physical appearance
• Almond eye

References

1. ^ MedlinePlus Medical Encyclopedia

External links

• Mother-daughter comparison photos
• Drawing of male face
• Drawing of female eye

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