Having an abnormal number of digits (6 or more) can occur on its own, without any other symptoms or disease. Polydactyly may be passed down (inherited) in families. This trait involves only one gene that can cause several variations.
African Americans, more than other ethnic groups, can inherit a 6th finger. In most cases, this is not caused by a genetic disease.
Polydactyly can also occur with some genetic diseases.
Extra digits may be poorly developed and attached by a small stalk (generally on the little finger side of the hand). Or, they may be well-formed and may even function. Poorly formed digits are usually removed. Simply tying a tight string around the stalk can cause it to fall off in time if there are no bones in the digit.
Larger digits may need surgery to be removed. The doctor should ask the parents whether there was polydactyly at birth, because a person may not know they have it.