ABO System
Definition
The blood-group classification described by Karl Landsteiner in 1901: groups A, B, AB, and O, defined by antigens on red-cell surfaces and corresponding antibodies in plasma. The first biological marker used for forensic population statistics.
- Discovered
- 1901 by Karl Landsteiner
- Gene location
- Chromosome 9
- Number of groups
- Four phenotypes: A, B, AB, O
Common questions
What are the ABO blood groups?+
The ABO system divides blood into four groups: A, B, AB, and O. Each group is determined by antigens on the surface of red blood cells. The groups also have corresponding antibodies in the plasma.
Why is the ABO system important in forensic work?+
The ABO system was the first biological marker used for forensic population statistics. Blood-group typing helps establish whether blood evidence could have come from a particular person.
What controls ABO blood group?+
The ABO gene located on chromosome 9 controls which blood group a person has. The antigens A and B are built on a precursor called the H antigen.
Related terms
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...
- Agglutination
- Clumping of red cells that occurs when antibodies in serum bind to incompatible antigens on the cell surface, cross-linking cells into visible...
- Antibody (Isohaemagglutinin)
- An immunoglobulin in plasma directed against red-cell antigens the host does not carry. Group O serum carries anti-A and anti-B; group AB...
- Antigen
- A molecule recognised by the adaptive immune system through specific binding to an antibody or T-cell receptor. Defined by immunogenicity (capacity to...
- Bombay Phenotype (Oh, Hh)
- Y. M. Bhende, 1952, K.E.M. Hospital Mumbai. Homozygous absence of the H antigen, so neither A nor B can be expressed; types...
- Forensic Serology
- The branch of forensic science concerned with detecting and characterising biological fluids (blood, semen, saliva, vaginal secretions) as evidence in legal proceedings,...
- ISBT
- International Society of Blood Transfusion. The authority that catalogues and numbers the 35+ recognised blood group systems.
- Lateral-Flow Immunoassay
- A point-of-care competitive immunochromatographic format on a nitrocellulose strip. In the absence of drug, colloidal gold-labelled antibody is captured at a test...
- MNS System
- A blood group system comprising M and N antigens on glycophorin A (GYPA) and S and s antigens on glycophorin B (GYPB)....
- Precipitin Test
- A serological method in which an antiserum specific to one species' proteins is mixed with an extract of an unknown specimen. Formation...
- Presumptive Test
- A fast, low-cost, class-specific screen used to triage a caseload before instrumental work begins. Examples are Marquis reagent for opioids and amphetamines,...
- Rh System
- A blood group system defined by antigens on two proteins encoded by the RHD and RHCE genes on chromosome 1. The clinically...
Explained in these topics
- Blood Group Systems in Forensic Science: ABO, Rh, MNS and BeyondKarl Landsteiner, 1901. Antigens A and B built on the H precursor. Four phenotypes: A, B, AB, O. Controlled by the ABO gene on chromosome 9.
- Scope and History of Forensic SerologyThe blood-group classification described by Karl Landsteiner in 1901: groups A, B, AB, and O, defined by antigens on red-cell surfaces and corresponding antibo...