Polydactyly and syndactyly
Polydactyly and syndactyly are congenital conditions characterized by the presence of extra digits or the fusion of digits, respectively. Polydactyly involves having additional fingers or toes, which can vary in development from rudimentary to fully functional. This condition occurs due to abnormal fetal development and may be hereditary, with the most common type being postaxial polydactyly. In contrast, syndactyly refers to two or more fingers or toes that are joined or fused together, often occurring in the middle and ring fingers or the second and third toes. Both conditions typically do not interfere with normal function and are primarily addressed for cosmetic reasons. Treatment usually involves surgical intervention, particularly for more complex cases. While these conditions have existed throughout history, they are often associated with various genetic factors and can occur alongside other developmental disorders. Awareness and understanding of polydactyly and syndactyly continue to evolve, reflecting both medical advances and cultural representations over time.
Polydactyly and syndactyly
ALSO KNOWN AS: Supernumerary digits, extra digits, polydactylia, polydactylism, hyperdactyly, syndactylia, syndactylism
ANATOMY OR SYSTEM AFFECTED: Blood vessels, bones, feet, hands, skin
DEFINITION: Polydactyly is the presence of extra fingers or toes; syndactyly describes two or more fingers or toes that are joined or fused together
CAUSES: Genetic or inherited; may occur as symptom of more than one hundred different inherited and developmental disorders
SYMPTOMS: In polydactyly, extra digit(s) varying from poorly developed without bone to fully developed and functional; in syndactyly, fusion of one or more digits
DURATION: Lifelong unless corrected
TREATMENTS: Surgery to remove extra digits or separate fused ones
Causes and Symptoms
Neither nor are serious congenital deformities, and they generally occur with no underlying or apparent cause. Both conditions may be genetic or inherited or may occur as a symptom of more than one hundred different inherited and developmental disorders. Sometimes there is not enough information to determine the cause, while other cases may be due to exposure during to toxins such as cigarette smoking or the drug or to poorly controlled diabetes during pregnancy. The hereditary aspects of the conditions are still being studied.
Polydactyly can vary from a poorly developed that is almost unnoticeable and without bone to a fully developed and functional digit. The condition occurs during fetal development when normal programmed cell death between digits fails to occur. In inherited cases, the genes responsible for the condition are dominant, which means that male and female children are equally likely to have the condition. Postaxial polydactyly is the most frequent form and accounts for about 75 to 80 percent of all cases. This type occurs in approximately one of every one thousand Caucasian births. African Americans are ten times more likely than any other ethnic group to have this type of polydactyly in the hand. One-half of polydactyly cases are bilateral, affecting both sides of the body, with the remainder of the cases affecting the left side almost twice as often as the right. Postaxial polydactyly is most often found in the hands and rarely found in both the hands and feet. People of Asian ancestry tend to have more occurrences of preaxial polydactyly, while central polydactyly is uncommon across all ethnic groups. All three types of polydactyly are believed to be inherited differently, although people in the same family may have different degrees of the condition.
In syndactyly, one or more digits fail to separate during fetal development. Syndactyly is one of the most common congenital malformations and occurs in about one of every 2,000 to 2,500 births. It is more common in males and Caucasians and usually affects the middle and ring fingers. In the toes, the condition most commonly affects the second and third toes. Incidents of syndactyly affect the left and right sides and the hands and feet equally and are usually bilateral. Syndactyly is described as either simple, in which the digits are fused by skin and soft tissue, or complex, in which the are also fused. The severity can range from incomplete webbing of the skin to sharing of the bones, nails, nerves, and blood vessels. Complicated syndactyly describes the addition of extra bones and unusual or development. Partial or incomplete syndactyly means that only part of the length of the digits are fused together. Complete syndactyly means that the entire length of the digits are fused together.
Treatment and Therapy
In most cases, polydactyly and syndactyly do not interfere with normal hand or foot function, and correction is done for cosmetic purposes. The conditions can be diagnosed at birth or by fetal ultrasound (sonogram). Once the condition is observed, physicians will normally require x-rays to determine its complexity.
In type A polydactyly, where the fully formed digit has bones, surgery is required when the baby is about a year old. In type B polydactyly, the digit is rudimentary, contains no bones, and is usually removed before the infant leaves the hospital. Many people are unaware that they ever had polydactyly. Central polydactyly is more complex, may affect normal hand or foot function, and often requires multiple surgeries.
Multiple surgeries may be needed to separate the digits in complex or complicated cases of syndactyly, and the procedures are usually performed when the child is between six months and eighteen months old. Skin grafts are typically taken from the lower to cover the newly separated digits. If multiple digits are involved, then more than one surgery may be needed as only one digit is separated at a time. Some children also experience recurrent syndactyly, or “web creep,” if there are complications in healing. In the feet, simple syndactyly is a cosmetic problem that is generally not treated unless surgery is desired.
Perspective and Prospects
Polydactyly and syndactyly have existed throughout history, and polydactyly is mentioned in the Bible in a description of a member of Goliath’s family (2 Samuel 21:20). Italian painter Raphael (1483–1520) depicted polydactyly in at least six of his works, including The Marriage of the Virgin (1504) and La Belle Jardiniere (1507). The examination of polydactyly through several generations of a Berlin family by French mathematician, biologist, and astronomer Pierre-Louis Moreau de Maupertuis (1698–1759) is considered the first scientific analysis of a dominant inherited trait in humans.
Some famous polydactyls include King Charles VIII of France, Prime MinisterWinston Churchill of England, Major League Baseball pitcher Antonio Alfonseca, Bollywood actor Hrithik Roshan, actress Gemma Arterton, jazz pianist Hampton Halls, blues guitarist Hound Dog Taylor, Roman era poet Volcatius Sedigitus, and possibly Anne Boleyn, one of Henry VIII’s wives. A few famous syndactyls are Soviet leader Joseph Stalin; actors Ashton Kutcher, Dan Aykroyd, and Tricia Hefler; singer Rachel Stevens; and writers Rob Never and Mike Holderness. There is also some speculation that painter and inventor Leonardo da Vinci had syndactyly on his left hand.
Bibliography
Blereau, Robert P. “Polydactyly.” Consultant 39, no. 12 (December, 1999): 3297.
Flatt, Adrian E. “Webbed Fingers.” Baylor University Medical Center Proceedings 18 (January, 2005): 26.
Goldenring, John. "Webbing of the Fingers or Toes." MedlinePlus, December 1, 2011.
"Syndactyly (Webbed Digits)." Cleveland Clinic, 25 July 2022, my.clevelandclinic.org/health/diseases/23521-syndactyly-webbed-digits. 7 Apr. 2024.
“True Polydactyly.” Consultant 43, no. 10 (September 1, 2003): 1309.
Kaneshiro, Neil. "Polydactyly." MedlinePlus, November 7, 2011.
Kyriazis, Zisis. "Polydactyly: Clinical and Molecular Manifestations." World Journal of Orthopedics, 18 Jan. 2023, doi.org/10.5312%2Fwjo.v14.i1.13. Accessed 7 Apr. 2024.
Vorvick, Linda J. "Repair of Webbed Fingers or Toes." MedlinePlus, August 11, 2012.
Wynbrandt, James, and Mark D. Ludman. “Polydactyly.” In The Encyclopedia of Genetic Disorders and Birth Defects. 2d ed. New York: Facts On File, 2000.