The term human blood group systems is defined by the
International Society of Blood Transfusion
The International Society of Blood Transfusion (ISBT) is a scientific society founded in 1935, which promotes the study of blood transfusion and spreads reliable information about the ways in which blood transfusion medicine and science can bes ...
(ISBT) as systems in the human species where cell-surface
antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune respon ...
s—in particular, those on blood cells—are "controlled at a single gene
locus or by two or more very closely linked
homologous genes with little or no observable
recombination between them", and include the common
ABO and
Rh (Rhesus) antigen systems, as well as many others; 43 human systems are identified .
Table of systems and classifications
Antibodies
Following is a comparison of clinically relevant characteristics of antibodies against the main human blood group systems:
Compatibility testing
Blood compatibility testing is performed before
blood transfusion
Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...
, including matching of the
ABO blood group system
The ABO blood group system is used to denote the presence of one, both, or neither of the A and B antigens on erythrocytes. For human blood transfusions, it is the most important of the 43 different blood type (or group) classification system ...
and the
Rh blood group system, as well as screening for recipient antibodies against other human blood group systems. Blood compatibility testing is also routinely performed on pregnant women and on the
cord blood
Cord blood (umbilical cord blood) is blood that remains in the placenta and in the attached umbilical cord after childbirth. Cord blood is collected because it contains stem cells, which can be used to treat hematopoietic and genetic disorders s ...
from newborn babies, because incompatibility puts the baby at risk for developing
hemolytic disease of the newborn.
It is also used before
hematopoietic stem cell transplantation, as it may be responsible for some cases of acute
graft-versus-host disease
Graft-versus-host disease (GvHD) is a syndrome, characterized by inflammation in different organs. GvHD is commonly associated with bone marrow transplants and stem cell transplants.
White blood cells of the donor's immune system which remain ...
.
Other human blood group systems than ABO and Rh have a relatively small risk of complications when blood is mixed.
Therefore, in emergencies such as major
hemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
, the urgency of transfusion can exceed the need for compatibility testing against other blood group systems (and potentially Rh as well).
Also, blood compatibility testing beyond ABO and Rh is generally limited to antibody detection (not necessarily including forward typing). Still, in Europe, females who require blood transfusions are often typed for the
K and extended Rh antigens to prevent sensitization to these antigens, which could put them at risk for developing
hemolytic disease of the newborn during pregnancy.
When needing to give red blood cell transfusion to a patient, the presence of clinically significant antibodies produced by the patient can be detected by mixing patient serum with 2 to 4 "screening" or "control" red blood cells that together display essentially all relevant antigens. If any of these mixes display a reaction (evidence of patient antibodies binding to the screening red blood cells), a more extensive antibody panel is warranted (as imaged at right).
References
Further reading
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ISBT Table of blood group antigens within systems updated August 2008.
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BGMUT
The BGMUT (Blood Group antigen gene MUTation) Database documents allelic variations in the genes encoding for human blood group systems. It was set up in 1999 through an initiative of the Human Genome Variation Society ( HGVS). Since 2006, it has b ...
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Blood Group Antigen Gene Mutation Database at
NCBI,
NIH.
External links
BGvar a comprehensive online resource for blood group associated genetic variants.
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{{Transfusion medicine
Blood antigen systems
Transfusion medicine