This congenital abnormality is characterized by limb (hand or feet) anomalies. In many cases, bones are missing from the fingers and the whole finger may be missing also. The ends of the hand may have "nubbins" - small stumps where the finger would have developed, which may have tiny residual nails.

Unfortunately, the cause of such cases is not discovered yet, though some scientists believe that it might be caused by an interruption of the blood supply when an arm starts developing at four to six weeks of pregnancy. There is no link to the behavior of the mother during her pregnancy. For a mother there is almost no risk to have two children with such a condition, and the abnormality is also not passed to the children from their parents.

Often children born with symbrachydactyly easily adapt to their physical limitations and live full and normal life, even without constant treatment.

More Info: en.wikipedia.org