There are different types of birth defects that affect the hand. One of the most common is syndactyly, in which two or more fingers are fused together. Other common defects include short, missing or deformed fingers, tendons that don't move or abnormal nerves or blood vessels
Causes and Risk Factors
It is not known what causes these defects. There may be an inherited element or it may be the result of something that happened during the baby's development before birth.