Brachydactyly, Type A4, also known as brachymesophalangy ii and v, is related to brachydactyly-syndactyly syndrome and brachydactyly, type a2. An important gene associated with Brachydactyly, Type A4 is HOXD13 (Homeobox D13), and among its related pathways/superpathways are Elastic fibre formation and G-protein signaling_Rap2B regulation pathway. Affiliated tissues include bone and heart, and related phenotypes are short middle phalanx of the 5th finger and shortening of all middle phalanges of the toes