- Also called:
- hyperdactyly
- Related Topics:
- digit
- digit malformation
- On the Web:
- National Center for Biotechnology Information - Supernumerary Digit (Oct. 25, 2026)
polydactyly
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What is polydactyly?
Polydactyly is a congenital condition where a person is born with more than five fingers on a hand or toes on a foot. The extra digit can range from a small bump to a fully functioning finger or toe. Polydactyly is categorized into preaxial (duplication of the thumb or big toe), central (additional digit near the middle digits), and postaxial (extra little toe or finger) types.
The causes of polydactyly are not fully understood, but genetics or environmental factors disrupting limb growth during fetal development can be factors. Polydactyly can be treated through surgery or by tying off the extra digit.
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How does polydactyly affect a person's fingers or toes?
Polydactyly is a congenital condition where a person has more than five fingers or toes. The additional digit can range from a small bump to a fully functioning finger or toe. In complex cases, the extra digit comprises skin, soft tissue, bone, joints, ligaments, or tendons.
There are three types of polydactyly: preaxial (duplication of the thumb or big toe), central (additional digit near the middle digits), and postaxial (extra little finger or toe). The extra digit may be an isolated symptom or part of a syndrome like Down syndrome. Treatment ranges from tying off the extra digit to surgical removal.
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Is polydactyly inherited from parents?
Yes, in some instances, polydactyly can be inherited from parents. For example, if one parent carries the affected gene, there is a 50% chance that the individual will be born with the condition, as it is a dominant trait. Polydactyly can also be caused by genetic disorders or environmental factors that disrupt limb growth during fetal development.
There are three types of polydactyly: preaxial, central, and postaxial. In any type, the extra digit may appear as a lone symptom of non-syndromic polydactyly, or it may occur as syndromic polydactyly, in which it accompanies other congenital anomalies as part of a syndrome.
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Are there different types of polydactyly?
Polydactyly, characterized by more than the usual number of digits, is divided into three types: preaxial, central, and postaxial. Preaxial polydactyly involves duplication of the thumb or big toe. Central polydactyly involves an additional digit near the middle digits. Postaxial polydactyly involves an extra little toe or finger.
The extra digit can be an isolated case of non-syndromic polydactyly or part of syndromic polydactyly, occurring with other congenital anomalies such as Down syndrome. Polydactyly sometimes occurs in genetic syndromes, including chromosomal trisomy 13 and Ellis–van Crevald syndrome. In some people, polydactyly is a dominant trait, meaning that if one parent carries the affected gene, the individual has a 50% chance of having the condition. Genetic disorders or environmental factors that disrupt limb growth during fetal development can also cause polydactyly.
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How is polydactyly treated or managed by doctors?
Polydactyly is a congenital condition involving more than five digits on a hand or foot. Treatment varies depending on the digit's complexity.
Simple cases may be treated by tying off the extra digit, causing it to fall off. However, this is not recommended when the digit has nerves, veins, and arteries due to potential pain and neuroma formation. Complex cases are typically resolved with surgery, usually performed between one and two years of age. Surgical removal is favored in complex cases involving bone, joints, ligaments, or tendons.
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polydactyly, condition that is present at birth in which a person has more than five fingers on a hand or more than five toes on a foot. The term polydactyly is derived from the Greek words poly, meaning “many,” and daktylos, meaning “digit.” Polydactyly occurs in an estimated 1 in 500–1,000 births, with variation from 1 in roughly 1,330 births among white people to 1 in 143 births among Black people. In general, the condition affects males and females equally. Many children with polydactyly are otherwise healthy individuals.
Polydactyly can present in various ways: in some instances, an extra digit is visible as a small bump (or “nubbin”), whereas in other instances, the digit is a fully functioning extra finger or toe. Rarely, individuals are born with extra digits on both the hands and the feet. Often the extra digit is made up of skin and soft tissue and may include a bone. More-complex cases of polydactyly involve a combination of skin, soft tissue, and bone, along with a joint, ligament, or tendon.
Types and causes of polydactyly
Polydactyly can be divided into three types: preaxial, central, and postaxial. Preaxial polydactyly is characterized by the duplication of the thumb or big toe. Central polydactyly is characterized by an additional digit near the middle digits, such as between the second and third toe or the third and fourth toe or between the index and middle finger or the middle and ring finger. Postaxial polydactyly is characterized by an extra little toe or finger (the “pinkie” toe or finger). In any type of polydactyly, the extra digit may appear as a lone symptom of so-called non-syndromic polydactyly, or it may occur as syndromic polydactyly, in which it accompanies other congenital anomalies as part of a syndrome (e.g., polysyndactyly [polydactyly with webbing between or fusion of adjacent digits], Down syndrome, or trisomy 13).
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The underlying pathophysiology of polydactyly is not fully known. In some instances, the condition appears to be inherited. For example, in some persons, polydactyly is a dominant trait, meaning that if one of an individual’s biological parents carries the affected gene, the individual has a 50 percent chance of being born with the condition. Genetic disorders or environmental factors that disrupt limb growth during fetal development can cause polydactyly.
Treatment
Polydactyly may be treated by tying off the extra digit; the digit shrivels and eventually falls off. This technique is not used when extra digits have a nerve, a vein, and an artery, since pain can result during digit removal. Tying off also carries a risk of incomplete removal, in which a neuroma (a painful bump) develops, because the body tries to regrow the nerve of the extra digit. In complex cases, extra digits are removed with surgery, typically when an individual is between ages one and two.