Polydactyly
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Polydactyly, or polydactylism, is the anatomical abnormality of having more than the usual number of digits on the hands or feet. It is a congenital abnormality, usually genetically inherited as an autosomal dominant trait.
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Overview
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In humans, it is usual to have five digits (four fingers and one thumb) on each hand, and five digits (toes) on each foot. Polydactyls have six or maybe even more digits on either their hands or feet, or both. The extra digits vary from small pieces of soft tissue to apparently complete digits. In Western societies, they are usually surgically removed during early life.
The condition is reported in about 2 children in every thousand, although the frequency varies greatly from population to population. It is higher in some groups (e.g. the Pennsylvania Dutch in the United States) due to the founder effect.
Historically and in the contemporary world, polydactyly has been associated with witchcraft, psychic power, the extraterrestrial, divine connection, and sporting prowess.
Types of polydactyly
There are several types of polydactyly, of varying frequency. Here are some of them:
- Polydactyly alopecia seborrheic dermatitis
- Polydactyly cleft lip palate psychomotor retardation
- Polydactyly myopia syndrome
- Polydactyly postaxial dental and vertebral
- Polydactyly postaxial with median cleft of upper lip
- Polydactyly postaxial
Missing image Polydactyly_01_Lfoot_AP.jpg Left foot with postaxial polydactly of 5th ray | Missing image Polydactyly_01_Rfoot_AP.jpg Right foot with postaxial polydactly of 5th ray |
- Polydactyly preaxial type 1
- Polydactyly syndrome middle ray duplication
Missing image Polydactyly_01_Lhand_AP.jpg Left hand with mid ray duplication | Missing image Polydactyly_01_Rhand_AP.jpg Right hand with mid ray duplication |
- Polydactyly visceral anomalies cleft lip palate
Related articles
External links
- Polydactyly and Syndactyly (http://www.hmc.psu.edu/healthinfo/pq/poly.htm)
- Polydactylism FAQ (http://www.drgreene.com/21_182.html)
- Article on polydactylism in cats in New England (http://www.straightdope.com/mailbag/m6toecat.html)de:Polydaktylie