Your blood type depends on the presence or absence of specific substances on the surface of red blood cells. Red blood cells are the portion of blood responsible for carrying oxygen throughout the body. These substances, called antigens, are made of mostly protein and carbohydrates and differ from person to person. Blood groups—the most familiar being A, B and O—are descriptions of certain antigens found on red cells.

People with type A blood have A antigens on their red blood cells and lack B antigens; people with type B blood have B antigens and lack A antigens; people with type AB blood have both antigens, and people with type O blood lack both A and B antigens but have others.

However, there are more than 600 known antigens besides A and B that characterize the proteins found on a person's red cells. A combination of some of these less familiar but commonly occurring antigens are absent from the blood of an extremely small percentage of the population. There are also a few antigens that almost all people have on their red cells but that some lack. In either case—whether a person's blood has uncommon antigens or lacks common antigens—the person is usually categorised as having a rare blood type. A person's blood type is considered rare if only one other person in 1,000 lacks the same antigens or shares the same uncommon antigens. A person's blood type is considered very rare if only 1 person in 10,000 has or lacks similar antigens.

The human body naturally manufactures antibodies, even without ever having a transfusion, to the ABO antigens not present on its own red blood cells because it recognizes those antigens as foreign. For instance, people who are group A make anti-B. People who are group O make anti-A and anti-B, since they do not have either antigen on their red cells. When a patient requires a transfusion, the blood he or she receives must not interact with these antibodies to prevent a potentially life-threatening reaction. For example, a patient who is group A has anti-B, so transfused blood must not be group B or group AB since these red cells carry the B antigen. When a person has a rare blood type and has formed the corresponding antibody, it becomes even more crucial to quickly find donor blood that lacks the same antigens.

The goal of the RareBloodGroups.Org is to maintain an up-to-date registry of all donors with these rare blood types so that any patient in need can quickly be transfused with blood that is safe for him or her.

At present we are registering only Bombay Blood Group , AB Negative , B Negative , O Negative and A Negative .

Please click here to become our rare blood group donor