Radio-Ulnar Synostosis-Amegakaryocytic Thrombocytopenia Syndrome, also known as atrus syndrome, is related to synostosis and thrombocytopenia, and has symptoms including petechiae of skin An important gene associated with Radio-Ulnar Synostosis-Amegakaryocytic Thrombocytopenia Syndrome is HOXA11 (Homeobox A11). Affiliated tissues include bone and skin, and related phenotypes are clinodactyly of the 5th finger and radioulnar synostosis