The Indian blood group system (ISBT: IN/023) consists of two antithetical antigens: Ina(IN1), which is present in approximately 10 percent of some Arab populations and in 3 percent of Bombay Indians, and its allelic antigen Inb(IN2), an antigen of high incidence in all populations. In 2007, two new high-incidence antigens were identified as belonging to the IN blood group system, namely IN3 (INFI) and IN4 (INJA). The antigens in this system are located on CD44, a single-pass membrane glycoprotein that is encoded by the