Description, Causes and Risk Factors:

Polydactyly means having more than five fingers and five toes on each hand or foot. The presence of an extra digit can range from just an extra nub of flesh to a fully formed finger complete with bone structure. Some extra digits are fully functional while others aren't.

Polydactyly is, in most cases, caused by genetic factors. It is usually inherited as an autosomal dominant characteristic. The gene that determines polydactyly is located on one of the short legs of chromosome seven. This is not the sex determining chromosome, therefore it is equally probable to occur in a female as it is in a male.

The gene is a dominant expressive gene and therefore needs to come from both parents. The condition stems from a mutation in the DNA that causes the congenital defect. Since polydactyly is a dominantly expressed gene, if a child has one parent that is polydactyly then, based on genetic probabilities, there is a fifty-fifty chance the child will have it too. Using this information, it may be possible to trace a family's history by tracing the possession of extra digits on the hand or foot.

The occurrence of this condition can be isolated or it can be a symptom of another disease. Over a hundred diseases include polydactyly as a symptom. A few of the other genetic diseases that present with the appearance of extra appendages include Carpenter's syndrome, asphyxiating thoracic dystrophy and Rubinstein-Taybi syndrome.

Most occurrences of the condition, though, can be traced to genetic factors. Unfortunately, genetic histories can be difficult to obtain past a few generations. Furthermore, the condition is frequently not discussed and some may never know that there is a history of developing extra fingers or toes in the family. The gene expression that gives rise to polydactyly can express in a number of ways. The expression may take the form of a poorly developed finger that can be removed easily due to the lack of any bone structure, or it may present as an almost fully formed or fully formed finger that can be retained and even be utilized. For larger digits, if the decision is made to have the extra finger or toe removed, surgery may be necessary.


Signs and Symptoms:

    A small extra bump on the side of the hand.

  • A finger which widens to end in two fingertips.

  • An extra finger which dangles by a thin cord from the hand.

  • A hand which looks normal except that it has a thumb and five fingers.

  • An infinite number of other variations.


The doctor will diagnose the condition based on a family history, medical history, and physical examination.

Medical history questions may include:

    Have any other family members been born with extra fingers or toes?

  • Is there a known family history of any of the disorders linked to polydactyly?

  • Are there any other symptoms or problems?

Tests used to diagnose the condition:

    Chromosome studies.

  • Enzyme tests.

  • X-rays.

  • Metabolic studies.

After seeing your health care provider, you may want to add a note to your personal medical record about polydactyly, its diagnosis, and treatment.

During pregnancy, this condition may be diagnosed with ultrasound or a more advanced test called embryofetoscopy during the first three months (trimester).

While the possession of an extra digit on your hand or foot is not a life threatening condition, you should have it evaluated by your family doctor during a check-up. It can be an indicator of genetic problems or diseases that hasn't cropped up as of yet. The genetic diseases can be very serious. Furthermore, for some, having the extra digit removed early on in life will present fewer social problems.


The main treatment of polydactyly is surgery to remove the extra parts and more importantly to correct associated problems with what remains. This is sometimes fairly complicated surgery, because there may be variations in all of the structures of the digit which is kept - twisted bones, crooked joints, missing or extra tendons, nerves, and blood vessels. Abnormalities in the fingers which are kept may be more obvious after surgery than before, but with careful planning, a hand surgery specialist will attempt to anticipate and correct these problems at the time of surgery. After surgery, it is usual to protect the hand in a large bandage for weeks to months, depending on what is done. Surgery done in childhood may need to be adjusted for growth with "touch up" surgery when the child is older.

A hand therapist can help with some problems before and after surgery, tailored to the individual problem and the temperament of the child, but some children proceed through their surgery and recovery without needing therapy.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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