Wiktionary
n. A congenital abnormality of the hand, characterized by missing or malformed fingers.
Wikipedia
Symbrachydactyly is a congenital abnormality, characterized by limb anomalies consisting of brachydactyly, cutaneous syndactyly and global hypoplasia of the hand or, foot. In many cases, bones will be missing from the fingers and some fingers or toes may be missing altogether. The ends of the hand may have "nubbins"—small stumps where the finger would have developed, which may have tiny residual nails.
Symbrachydactyly has been reported to appear without other combined limb anomalies and usually in one arm in 1 in 30,000 births to 1 in 40,000 births.
The cause of symbrachydactyly is unknown. One possible cause might be an interruption of the blood supply to the developing arm at four to six weeks of pregnancy. There is no link to anything the mother did or did not do during pregnancy. There is also no increased risk of having another child with the same condition or that your child will pass the condition on to his or her children.
In most cases, children born with symbrachydactyly are able to adapt to their physical limitations and experience a fully functional life with no treatment. Possible treatment includes surgery or a routine of regularly stretching the fingers.
Symbrachydactyly may be associated with Poland syndrome, a disorder which includes a missing pectoral muscle as one of its symptoms.