Frequency of the A2-Subgroup Among Blood Group A and Blood Group AB Among Students of Faculty of Medicine and Health Sciences at Alimam Almahadi University, White Nile, Sudan

Antigens of the ABO blood group system (i.e., A, B, and H antigens) and Rhesus factor were discovered more than one century ago by karl & steiner [1,2] who is considering the father of transfusion medicine, and with this discovery he enabling physicians to transfuse blood without endangering the patient′s life. The ABO antigens are defined by carbohydrate moieties on the extracellular surface of the red blood cell (RBC) membranes [3], but they are also highly expressed on the surface of a variety of human cells and tissues, including epithelium, sensory neurons, platelets, and vascular endothelium [4]. The ABO and Rh blood group system remain the most important blood group systems and the classical immuno genetic markers [5,6]. Blood group antigens play a vital role in transfusion medicine, genetics understanding, inheritance pattern, and disease susceptibility [7]. ABO and Rh D system also have a key role in evolutionary biology, anthropology, studying migration patterns, forensic pathology, and medico-legal issues such as unmatched pregnancy and disputed paternity [8]. The frequency of ABO blood groups varies greatly in different races and populations. In most populations, about 50% are Group O, followed closely by group A, with groups B and AB showing a much lower incidence [3]. In Chinese population group B has higher frequencies [9] and it is the commonest group in the Bengalese population [10].