Brachydactyly type A3 is characterized by shortening of the middle phalanx of the little finger with radial deviation of distal phalanx. Slanting of the distal articular surface of the middle phalanx leads to radial deflection of the distal phalanx. However, it is not always associated with clinodactyly.
Type A3 brachydactyly is quite common among Japanese adolescent population. Incidences varies from 4-21% in different populations.
It is an autosomal dominant disorder like other subtypes of brachydactyly. However no gene or locus for BDA3 has yet been identified.