What are Blood Types?

Everybody has a Blood type. The most common Blood type classification system is the ABO system discovered and defined by Karl Landsteiner in the early 1900s. There are four types of Blood in the ABO system: A, B, AB, and O. Your Blood type is established before you are born, by specific genes inherited from your parents. You receive one gene from your mother and one gene from your father; these two combine to establish your Blood type. These two inherited genes determine your Blood type by making proteins called agglutinogens exist on the surface of each red Blood cell in your body. Blood test results are important in Blood disorders in Blood test and Blood tests with Rare Blood types.

There are three alleles (variations) of the Blood type gene: A, B, and O. Since we all have two copies of these genes in our Blood, there are six possible combinations; AA, BB, OO, AB, AO, and BO. These combinations are referred to as genotypes, and they describe the genes you got from your parents.

In addition to the proteins existing on your red Blood cells, other genes make proteins called agglutinins that circulate in your Blood plasma. Agglutinins are protectors of our bodies and are responsible for ensuring that only the Blood cells of our own particular Blood type exist in our bodies.

AB
People with Blood type AB negative (1/2% of the population) and AB positive are potential universal plasma donors. This means plasma can be transfused to people having all Blood types.

AB +
People with Blood type AB positive comprise 3-1/2% of the population. People with this type of Blood are universal recipients. This means that they can be transfused with any type of Blood in emergency situations. Facts about Blood Types with charts about Blood Types and Blood type information

O +
O positive donors are needed more frequently than any other donor. Because O positive is the most common Blood type (39% of the population), it is needed more often by people requiring Blood in hospitals. Facts about Blood Types with charts about Blood Types and Blood type information

O -
7% of the population has O negative Blood. People with O negative donors are potential universal red Blood cell donors. This means that their red Blood cells can be transfused to patients with all types of Blood. Facts about Blood Types with charts about Blood Types and Blood type information

Simply put, your Blood is tested for ABO/Rh. These tests identify your 'Blood type.' You may have A, B, O, or AB type Blood and may be either Rh+ or Rh-. The basis of the Blood group tests is the ability to detect specific substances, or antigens, on the red Blood cells. The A antigen is on type A cells; the B antigen is on type B cells. If neither A nor B antigens are detected, the donor has type O Blood; if both are present, the donor has type AB Blood. If the major Rh antigen is present, the donor is Rh+ (for example, O+, A+, B+, or AB+); if not, the donor is Rh- (O-, A-, B-, or AB-).

There are more than 600 other antigens that have now been identified on red Blood cells. These sub-types are important, but often not considered.