BloodTyping
Information
There are four main blood groups: A, B, AB, and O. Blood types are determined based on the antigens located on the red blood cells. For example, a person with type AB blood has both A and B antigens on his or her red blood cells. An individual with Type O blood does not have antigens on his or her cells. Type O individuals would produce antibodies against these antigens.
When different blood types are mixed, agglutination occurs. (The blood appears to “clump.”) This occurs because individuals who do not have a certain antigen on their blood cells will produce antibodies against that antigen. The antibodies and antigens mix, causing a reaction. This is why individuals cannot receive blood transfusions from just any donor. Type O blood is known as the universal donor; everyone can receive type O blood. Type O blood contains no antigens, therefore there is nothing that would generate an immune respose. People with Type AB blood can accept blood from any donor; type AB is the universal recipient.
Children inherit their blood types from their parents. Therefore, it is possible to use blood typing as a means of detecting the birth parents of a child. Because there is a limited number of blood types, the blood test does not give a definitive response. However, it can be used to eliminate potential candidates and narrow a search.
The A, B, or O blood group is determined by a single gene. Different blood types (phenotypes) are caused by different genotypes.
PHENOTYPE Genotypes
Type O IOIO
Type AB IAIB
Type A IAIA or IAIO
Type B IBIB or IBIO
Multiple alleles are involved in the determination of blood type. Genotypes for individuals with Type A and B blood can sometimes be harder to ascertain than those for individuals with O or AB. Additional information about the individual’s family will help to make those distinctions.
Click here to return to Blood Test Results