Polydactyly is the presence of excess fingers or toes. The most observed form is hexadactyly with the presence of 6 fingers or 6 toes. Surgical intervention may be considered.

Definition of polydactyly

Polydactyly is a medical term associated with

• the presence of one or more additional fingers on the hand;
• the presence of one or more additional toes on the foot.

The presence of an extra finger or toe is the most observed case. We speak of hexadactyly with 6 fingers or 6 toes. Polydactyly, however, can be characterized by the presence of more than two additional fingers or toes. Cases have already been described with the presence of more than 10 fingers on a hand, or 10 toes on a foot.

Polydactyly can affect a single hand or a single foot, but can also be bilateral. It is also estimated that it affects both hands or both feet in 50% of cases.

It is common to distinguish different types of polydactyly depending on the position of the extra fingers or toes. Although it is subject to certain disputes, this classification defines:

• praxial polydactyly when the extra finger is located on the side of the thumb or when the extra toe is located on the side of the big toe;
• postaxial polydactyly when the extra finger is located on the side of the little finger or when the extra toe is located on the side of the little toe;
• central polydactyly when the extra finger or toe is located in the center of the hand or foot. 

Cause de la polydactylie

Polydactyly is inherited. It can be isolated or accompanied by other signs. It is found in particular in certain syndromes such as:

• Pallister-Hall syndrome, which combines many abnormalities that can affect the face and limbs, as well as heart, respiratory, urogenital and nerve damage;
• Guttmacher syndrome which is a rare syndrome resulting in several malformations in the hands and feet.

Diagnostic de la polydactylie

Polydactyly is usually diagnosed on ultrasound during the first or second trimester of pregnancy. Polydactyly of the hand is often easier to identify than that of the foot. The diagnosis can be complicated by certain parameters including the position of the fetus and the amount of amniotic fluid.

People affected by polydactyly

Polydactyly is the most common malformation of the hand. It is opposed to ectrodactyly which corresponds to the partial or total absence of one or more fingers.

Polydactyly affects an average of 1 in 100 newborns. The male sex seems to be more often affected than the female sex.

Polydactyly is characterized by the presence of extra fingers or toes. It can cause functional and aesthetic discomfort. In this case, surgery may be considered.

Polydactyly can be associated with other signs, especially in cases of Pallister-Hall syndrome or Guttmacher syndrome.

The management of polydactyly is only surgical. It consists of removing the fingers or toes causing functional or aesthetic discomfort.

Scientific studies have so far failed to identify preventive measures.