Polydactyly of the Hand
This condition is a common congenital anomaly that results in extra fingers or thumbs. Polydactyly can affect one or both hands and can result in one or more extra digits. Polydactyly can also affect the feet, resulting in extra toes.
This condition is caused by a genetic mutation that interferes with the normal development of the hand. As the fingers form, they fail to divide properly, instead of forming extra divisions that grow into whole or partial digits. In some cases, polydactyly occurs by itself, but often it occurs as a feature of a congenital disorder. People of African descent are more likely than other ethnic groups to inherit an extra finger without the presence of a congenital disorder.
Polydactyly most commonly results in a small extra finger attached to the little finger or attached to the hand next to the little finger. The extra digit may be fully formed and may even be fully functional, or it may be poorly formed and connected by only a small piece of skin. In some cases, the extra finger may appear as just a small bump on the hand. Another common variation of polydactyly results in the tip of the thumb or finger splitting to form two ends.
Extra digits are often surgically removed shortly after birth. A hand surgeon can evaluate the finger and determine the appropriate treatment.