Latin plica palpebronasalis FMA 59370 | TA A15.2.07.028 | |
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Epicanthic fold (/ɛpɪˌkænθɪk ˈfoʊld/), epicanthal fold, epicanthus, and eye fold are names for a skin fold of the upper eyelid, covering the inner corner (medial canthus) of the eye. Other names for this trait include plica palpebronasalis and palpebronasal fold. One of the primary facial features that is often closely associated with the epicanthic fold is elevation of the nasal bridge. All else equal, a lower-rooted nasal bridge is more likely to cause epicanthic folds, and a higher-rooted nasal bridge is less likely to do so. There are various factors that influence whether someone has epicanthic folds, including geographical ancestry, age, and certain medical conditions.
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Geographic distribution
Epicanthic folds appear in East Asians, Southeast Asians, Central Asians and some South Asians, Indigenous Americans, the Khoisan, Madagascar, and occasionally in Europeans (e.g., Scandinavians, Hungarians, Samis, Irish and Poles) and among Nilotes.
Anthropologist Carleton S. Coon states that the "median fold" occurs in Finnic and Slavic populations, while the "true inner or mongoloid fold" appears in populations of the east and the far north.
Age
Many fetuses lose their epicanthic folds after three to six months of gestation.
Medical conditions
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 have prominent epicanthic folds. 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 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.
In Zellweger syndrome, epicanthic folds are prominent. Other examples are fetal alcohol syndrome, phenylketonuria, and Turner syndrome.