1. Family history of polydactyly
2. Maternal diabetes
3. Maternal use of certain medications during pregnancy
4. Exposure to certain environmental toxins during pregnancy
5. Certain genetic syndromes, such as Down syndrome or Turner syndrome
6. Certain chromosomal abnormalities, such as trisomy 13 or trisomy 18

1. Surgery: This is the most common treatment for polydactyly of an index finger. The extra digit is removed surgically, and the remaining finger is reshaped to look like a normal index finger.

2. Splinting: This is a non-surgical option for treating polydactyly of an index finger. A splint is placed on the finger to help reshape it and encourage the finger to grow in a more normal shape.

3. Physical Therapy: Physical therapy can help to strengthen the muscles and tendons in the finger, which can help to improve the appearance of the finger.

4. Orthotics: Orthotics can be used to help support the finger and help it to grow in a more normal shape.

The causes of polydactyly of an index finger can vary, but the most common cause is a genetic mutation. Other causes can include environmental factors, such as exposure to certain chemicals or radiation, or a chromosomal abnormality. In some cases, the cause is unknown.

The most common symptom of polydactyly of an index finger is an extra finger or digit on the side of the index finger. This extra digit may be fully formed or may be a small nub. Other symptoms may include webbing between the extra digit and the index finger, or the extra digit may be fused to the index finger.

Polydactyly of an index finger is a condition in which a person has an extra finger on their index finger. This extra finger may be a full-sized finger or a small nub. It is a congenital condition, meaning it is present at birth.