![ABO blood type](https://upload.wikimedia.org/wikipedia/commons/3/32/ABO_blood_type.svg)
The ABO blood group system is used to denote the presence of one, both, or neither of the A and B
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 respons ...
s on
erythrocyte
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s.
For human
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 ...
s, it is the most important of the 43 different
blood type (or group) classification systems currently recognized 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 ...
s (ISBT) as of June 2021.
A mismatch (very rare in modern medicine) in this, or any other
serotype, can cause a potentially fatal
adverse reaction after a transfusion, or an
unwanted immune response to an organ transplant.
The associated anti-A and anti-B
antibodies are usually
IgM
Immunoglobulin M (IgM) is one of several isotypes of antibody (also known as immunoglobulin) that are produced by vertebrates. IgM is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antig ...
antibodies, produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses.
The ABO blood types were discovered by
Karl Landsteiner
Karl Landsteiner (; 14 June 1868 – 26 June 1943) was an Austrian-born American biologist, physician, and immunologist. He distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from ...
in 1901; he received the
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
in 1930 for this discovery. ABO blood types are also present in other
primates such as
apes and
Old World monkeys
Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboon ...
.
History
Discovery
The ABO blood types were first discovered by an Austrian physician,
Karl Landsteiner
Karl Landsteiner (; 14 June 1868 – 26 June 1943) was an Austrian-born American biologist, physician, and immunologist. He distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from ...
, working at the Pathological-Anatomical Institute of the University of Vienna (now
Medical University of Vienna). In 1900, he found that red blood cells would clump together (
agglutinate) when mixed in test tubes with sera from different persons, and that some human blood also agglutinated with animal blood. He wrote a two-sentence footnote:
This was the first evidence that blood variations exist in humans – it was believed that all humans have similar blood. The next year, in 1901, he made a definitive observation that blood serum of an individual would agglutinate with only those of certain individuals. Based on this he classified human blood into three groups, namely group A, group B, and group C. He defined that group A blood agglutinates with group B, but never with its own type. Similarly, group B blood agglutinates with group A. Group C blood is different in that it agglutinates with both A and B.
This was the discovery of blood groups for which Landsteiner was awarded the
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
in 1930. In his paper, he referred to the specific blood group interactions as isoagglutination, and also introduced the concept of agglutinins (antibodies), which is the actual basis of
antigen-antibody reaction in the ABO system.
He asserted:
Thus, he discovered two antigens (agglutinogens A and B) and two antibodies (agglutinins – anti-A and anti-B). His third group (C) indicated absence of both A and B antigens, but contains anti-A and anti-B.
The following year, his students Adriano Sturli and Alfred von Decastello discovered the fourth type (but not naming it, and simply referred to it as "no particular type").
![UkrArmyBloodGroupIII+2000s](https://upload.wikimedia.org/wikipedia/commons/6/69/UkrArmyBloodGroupIII%2B2000s.jpg)
In 1910,
Ludwik Hirszfeld
Ludwik Hirszfeld (5 August 1884 – 7 March 1954) was a Polish microbiologist and serologist. He is considered a co-discoverer of the inheritance of ABO blood types.
Life
He was a cousin of Aleksander Rajchman, a Polish mathematician, and of ...
and
Emil Freiherr von Dungern
Baron Emil von Dungern (26 November 1867 – 4 September 1961) was a German internist.
Von Dungern was born in Würzburg and died in Ludwigshafen am Bodensee. In 1910–11, E. von Dungern and Ludwik Hirszfeld discovered the heritability of ...
introduced the term O (null) for the group Landsteiner designated as C, and AB for the type discovered by Sturli and von Decastello. They were also the first to explain the genetic inheritance of the blood groups.
[)]
Classification systems
![Jan Janský, 1902](https://upload.wikimedia.org/wikipedia/commons/a/a2/Jan_Jansk%C3%BD%2C_1902.jpg)
Czech serologist
Jan Janský
Jan Janský () (3 April 1873 in Smíchov, now Prague – 8 September 1921 in Černošice, near Prague) was a Czech serologist, neurologist and psychiatrist. He is credited with the classification of blood into four types (I, II, III, IV).Book ...
independently introduced blood type classification in 1907 in a local journal.
He used the Roman numerical I, II, III, and IV (corresponding to modern O, A, B, and AB). Unknown to Janský, an American physician
William L. Moss devised a slightly different classification using the same numerical;
his I, II, III, and IV corresponding to modern AB, A, B, and O.
These two systems created confusion and potential danger in medical practice. Moss's system was adopted in Britain, France, and US, while Janský's was preferred in most European countries and some parts of US. To resolve the chaos, the
American Association of Immunologists
The American Association of Immunologists (AAI) is an international scientific society dedicated to furthering the study of immunology. AAI provides its members with a variety of platforms in which to exchange ideas and present the latest immunolo ...
, the
Society of American Bacteriologists
The American Society for Microbiology (ASM), originally the Society of American Bacteriologists, is a professional organization for scientists who study viruses, bacteria, fungi, algae, and protozoa as well as other aspects of microbiology. It wa ...
, and the Association of Pathologists and Bacteriologists made a joint recommendation in 1921 that the Jansky classification be adopted based on priority.
But it was not followed particularly where Moss's system had been used.
In 1927, Landsteiner had moved to the
Rockefeller Institute for Medical Research
The Rockefeller University is a private biomedical research and graduate-only university in New York City, New York. It focuses primarily on the biological and medical sciences and provides doctoral and postdoctoral education. It is classi ...
in New York. As a member of a committee of the
National Research Council National Research Council may refer to:
* National Research Council (Canada), sponsoring research and development
* National Research Council (Italy), scientific and technological research, Rome
* National Research Council (United States), part of ...
concerned with blood grouping, he suggested to substitute Janský's and Moss's systems with the letters O, A, B, and AB. (There was another confusion on the use of figure 0 for German ''null'' as introduced by Hirszfeld and von Dungern, because others used the letter O for ''ohne'', meaning without or zero; Landsteiner chose the latter.
) This classification was adopted by the National Research Council and became variously known as the National Research Council classification, the International classification, and most popularly the "new" Landsteiner classification. The new system was gradually accepted and by the early 1950s, it was universally followed.
Other developments
The first practical use of blood typing in transfusion was by an American physician
Reuben Ottenberg
Reuben Ottenberg (1882 in New York City – 1959) was an American physician and haematologist, who served Mount Sinai Hospital in New York City with distinction for 50 years.
He received his B.A. from Columbia University in 1902 and his M.D. degr ...
in 1907. Large-scale application began during the First World War (1914–1915) when
citric acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...
began to be used for
blood clot prevention.
Felix Bernstein demonstrated the correct blood group inheritance pattern of multiple
allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
::"The chro ...
s at one locus in 1924.
Watkins and Morgan, in England, discovered that the ABO
epitope
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...
s were conferred by sugars, to be specific, N-acetylgalactosamine for the A-type and galactose for the B-type. After much published literature claiming that the ABH substances were all attached to glycosphingolipids, Finne ''et al''. (1978) found that the human erythrocyte glycoproteins contain polylactosamine chains that contains ABH substances attached and represent the majority of the antigens. The main glycoproteins carrying the ABH antigens were identified to be the Band 3 and Band 4.5 proteins and glycophorin. Later, Yamamoto's group showed the precise glycosyl transferase set that confers the A, B and O epitopes.
File:ABO blood group diagram.svg, Diagram showing the carbohydrate chains that determine the ABO blood group
File:Type A blood.png, Student blood test. Three drops of blood are mixed with anti-B (left) and anti-A (right) serum.
File:AP-Biology Final Project.svg, There are three basic variants of immunoglobulin antigens in humans that share a very similar chemical structure but are distinctly different. Red circles show where there are differences in chemical structure in the antigen-binding site (sometimes called the antibody-combining site) of human immunoglobulin. Notice the O-type antigen does not have a binding site.
Genetics
![ABO system codominance](https://upload.wikimedia.org/wikipedia/commons/c/ce/ABO_system_codominance.svg)
Blood groups are inherited from both parents. The ABO blood type is controlled by a single
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
(the
ABO gene) with three types of
allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
::"The chro ...
s inferred from
classical genetics
Classical genetics is the branch of genetics based solely on visible results of reproductive acts. It is the oldest discipline in the field of genetics, going back to the experiments on Mendelian inheritance by Gregor Mendel who made it possible ...
: ''i'', ''I
A'', and ''I
B''. The ''I'' designation stands for isoagglutinogen, another term for
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 respons ...
. The gene encodes a
glycosyltransferase
Glycosyltransferases (GTFs, Gtfs) are enzymes (EC 2.4) that establish natural glycosidic linkages. They catalyze the transfer of saccharide moieties from an activated nucleotide sugar (also known as the "glycosyl donor") to a nucleophilic glyco ...
—that is, an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
that modifies the
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
content of the
red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
antigens. The gene is located on the long arm of the
ninth chromosome (9q34).
The ''I
A'' allele gives type A, ''I
B'' gives type B, and ''i'' gives type O. As both ''I
A'' and ''I
B'' are dominant over ''i'', only ''ii'' people have type O blood. Individuals with ''I
AI
A'' or ''I
Ai'' have type A blood, and individuals with ''I
BI
B'' or ''I
Bi'' have type B. ''I
AI
B'' people have both
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...
s, because A and B express a special dominance relationship:
codominance
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
, which means that type A and B parents can have an AB child. A couple with type A and type B can also have a type O child if they are both heterozygous (''I
Bi'',''I
Ai''). The ''
cis-AB'' phenotype has a single enzyme that creates both A and B antigens. The resulting red blood cells do not usually express A or B antigen at the same level that would be expected on common group A
1 or B red blood cells, which can help solve the problem of an apparently genetically impossible blood group.
The table above summarizes the various blood groups that children may inherit from their parents.
Genotypes are shown in the second column and in small print for the offspring: AO and AA both test as type A; BO and BB test as type B. The four possibilities represent the combinations obtained when one allele is taken from each parent; each has a 25% chance, but some occur more than once. The text above them summarizes the outcomes.
Historically, ABO blood tests were used in
paternity testing, but in 1957 only 50% of American men falsely accused were able to use them as evidence against paternity. Occasionally, the blood types of children are not consistent with expectations—for example, a type O child can be born to an AB parent—due to rare situations, such as
Bombay phenotype and
cis AB.
Subgroups
The A blood type contains about 20 subgroups, of which A1 and A2 are the most common (over 99%). A1 makes up about 80% of all A-type blood, with A2 making up almost all of the rest.
[Blood Group A Suptypes](_blank)
The Owen Foundation. Retrieved 1 July 2008. These two subgroups are not always interchangeable as far as transfusion is concerned, as some A2 individuals produce antibodies against the A1 antigen. Complications can sometimes arise in rare cases when typing the blood.
With the development of
DNA sequencing, it has been possible to identify a much larger number of alleles at the ABO locus, each of which can be categorized as A, B, or O in terms of the reaction to transfusion, but which can be distinguished by variations in the
DNA sequence. There are six common
allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
::"The chro ...
s in white individuals of the
ABO gene that produce one's blood type:
The same study also identified 18 rare alleles, which generally have a weaker glycosylation activity. People with weak alleles of A can sometimes express anti-A antibodies, though these are usually not clinically significant as they do not stably interact with the antigen at body temperature.
Cis AB is another rare variant, in which A and B genes are transmitted together from a single parent.
Distribution and evolutionary history
The distribution of the blood groups A, B, O and AB varies across the world according to the population. There are also variations in blood type distribution within human subpopulations.
In the UK, the distribution of blood type frequencies through the population still shows some correlation to the distribution of
placenames
Toponymy, toponymics, or toponomastics is the study of ''toponyms'' (proper names of places, also known as place names and geographic names), including their origins, meanings, usage and types. Toponym is the general term for a proper name of ...
and to the successive invasions and migrations including
Celts
The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancien ...
,
Norsemen
The Norsemen (or Norse people) were a North Germanic ethnolinguistic group of the Early Middle Ages, during which they spoke the Old Norse language. The language belongs to the North Germanic branch of the Indo-European languages and is the pr ...
,
Danes,
Anglo-Saxons
The Anglo-Saxons were a Cultural identity, cultural group who inhabited England in the Early Middle Ages. They traced their origins to settlers who came to Britain from mainland Europe in the 5th century. However, the ethnogenesis of the Anglo- ...
, and
Normans
The Normans ( Norman: ''Normaunds''; french: Normands; la, Nortmanni/Normanni) were a population arising in the medieval Duchy of Normandy from the intermingling between Norse Viking settlers and indigenous West Franks and Gallo-Romans. ...
who contributed the
morpheme
A morpheme is the smallest meaningful constituent of a linguistic expression. The field of linguistic study dedicated to morphemes is called morphology.
In English, morphemes are often but not necessarily words. Morphemes that stand alone are ...
s to the placenames and the
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s to the population. The native Celts tended to have more type O blood, while the other populations tended to have more type A.
The two common O alleles, O01 and O02, share their first 261
nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecule ...
s with the group A allele A01.
However, unlike the group A allele, a
guanosine
Guanosine (symbol G or Guo) is a purine nucleoside comprising guanine attached to a ribose ( ribofuranose) ring via a β-N9- glycosidic bond. Guanosine can be phosphorylated to become guanosine monophosphate (GMP), cyclic guanosine monophosphate ...
base is subsequently deleted. A premature
stop codon
In molecular biology (specifically protein biosynthesis), a stop codon (or termination codon) is a codon (nucleotide triplet within messenger RNA) that signals the termination of the translation process of the current protein. Most codons in mess ...
results from this
frame-shift mutation
A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (gene insertion, insertions or genetic deletion, deletions) of a number of nucleotides in a DNA sequence that is not divisible by ...
. This variant is found worldwide, and likely predates human migration from
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. The O01 allele is considered to predate the O02 allele.
Some evolutionary biologists theorize that there are four main lineages of the ABO gene and that mutations creating type O have occurred at least three times in humans.
From oldest to youngest, these lineages comprise the following alleles: ''A101/A201/O09'', ''B101'', ''O02'' and ''O01''. The continued presence of the O alleles is hypothesized to be the result of
balancing selection Balancing selection refers to a number of selective processes by which multiple alleles (different versions of a gene) are actively maintained in the gene pool of a population at frequencies larger than expected from genetic drift alone. Balanci ...
.
Both theories contradict the previously held theory that type O blood evolved first.
Origin theories
It is possible that food and environmental antigens (bacterial, viral, or plant antigens) have
epitope
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...
s similar enough to A and B glycoprotein antigens. The antibodies created against these environmental antigens in the first years of life can cross-react with ABO-incompatible red blood cells that it comes in contact with during blood transfusion later in life. Anti-A antibodies are hypothesized to originate from immune response towards
influenza virus
''Orthomyxoviridae'' (from Greek ὀρθός, ''orthós'' 'straight' + μύξα, ''mýxa'' 'mucus') is a family of negative-sense RNA viruses. It includes seven genera: ''Alphainfluenzavirus'', ''Betainfluenzavirus'', '' Gammainfluenzavirus'', ' ...
, whose epitopes are similar enough to the α-D-N-galactosamine on the A glycoprotein to be able to elicit a cross-reaction. Anti-B antibodies are hypothesized to originate from antibodies produced against
Gram-negative bacteria
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
, such as ''
E. coli'', cross-reacting with the α-D-galactose on the B glycoprotein.
However, it is more likely that the force driving evolution of allele diversity is simply negative frequency-dependent selection; cells with rare variants of membrane antigens are more easily distinguished by the immune system from pathogens carrying antigens from other hosts. Thus, individuals possessing rare types are better equipped to detect pathogens. The high within-population diversity observed in human populations would, then, be a consequence of natural selection on individuals.
Clinical relevance
The carbohydrate molecules on the surfaces of red blood cells have roles in
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
integrity,
cell adhesion, membrane transportation of molecules, and acting as receptors for extracellular ligands, and enzymes. ABO antigens are found having similar roles on
epithelial cells as well as red blood cells.
Bleeding and thrombosis (von Willebrand factor)
The ABO antigen is also expressed on the
von Willebrand factor
Von Willebrand factor (VWF) () is a blood glycoprotein involved in hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thrombocytope ...
(vWF)
glycoprotein, which participates in
hemostasis
In biology, hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage). It is the first stage of wound healing. This involves coagulation, ...
(control of bleeding). In fact, having type O blood predisposes to bleeding, as 30% of the total genetic variation observed in plasma vWF is explained by the effect of the ABO blood group, and individuals with group O blood normally have significantly lower plasma levels of vWF (and
Factor VIII
Factor VIII (FVIII) is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans, factor VIII is encoded by the ''F8'' gene. Defects in this gene result in hemophilia A, a recessive X-linked coagulation disorder ...
) than do non-O individuals. In addition, vWF is degraded more rapidly due to the higher prevalence of blood group O with the Cys1584 variant of vWF (an amino acid
polymorphism in VWF): the gene for
ADAMTS13
ADAMTS13 (''a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13'')—also known as ''von Willebrand factor-cleaving protease'' (VWFCP)—is a zinc-containing metalloprotease enzyme that cleaves von Willebrand factor ( ...
(vWF-cleaving
protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...
) maps to human
chromosome 9
Chromosome 9 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome, as they normally do with all chromosomes. Chromosome 9 spans about 138 million base pairs of nucleic acids (the building blocks of D ...
band q34.2, the same
locus
Locus (plural loci) is Latin for "place". It may refer to:
Entertainment
* Locus (comics), a Marvel Comics mutant villainess, a member of the Mutant Liberation Front
* ''Locus'' (magazine), science fiction and fantasy magazine
** ''Locus Award' ...
as ABO blood type. Higher levels of vWF are more common amongst people who have had
ischemic stroke
A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop funct ...
(from blood clotting) for the first time. The results of this study found that the occurrence was not affected by ADAMTS13 polymorphism, and the only significant genetic factor was the person's blood group.
ABO hemolytic disease of the newborn
ABO blood group incompatibilities between the mother and child do not usually cause
hemolytic disease of the newborn
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis foetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five ...
(HDN) because antibodies to the ABO blood groups are usually of the
IgM
Immunoglobulin M (IgM) is one of several isotypes of antibody (also known as immunoglobulin) that are produced by vertebrates. IgM is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antig ...
type, which do not cross the placenta. However, in an O-type mother, IgG ABO antibodies are produced and the baby can potentially develop
ABO hemolytic disease of the newborn
In ABO hemolytic disease of the newborn (also known as ABO HDN) maternal IgG antibodies with specificity for the ABO blood group system pass through the placenta to the fetal circulation where they can cause hemolysis of fetal red blood cells wh ...
.
Clinical applications
In human cells, the ABO alleles and their encoded glycosyltransferases have been described in several oncologic conditions. Using anti-GTA/GTB monoclonal antibodies, it was demonstrated that a loss of these enzymes was correlated to malignant bladder and oral epithelia. Furthermore, the expression of ABO blood group antigens in normal human tissues is dependent the type of differentiation of the epithelium. In most human carcinomas, including oral carcinoma, a significant event as part of the underlying mechanism is decreased expression of the A and B antigens.
Several studies have observed that a relative down-regulation of GTA and GTB occurs in oral carcinomas in association with tumor development.
More recently, a genome wide association study (GWAS) has identified variants in the ABO locus associated with susceptibility to pancreatic cancer.
In addition, another large GWAS study has associated ABO-histo blood groups as well as FUT2 secretor status with the presence in the intestinal microbiome of specific bacterial species. In this case the association was with ''Bacteroides'' and ''Faecalibacterium spp''. ''Bacteroides'' of the same OTU (operational taxonomic unit) have been shown to be associated with inflammatory bowel disease, thus the study suggests an important role for the ABO histo-blood group antigens as candidates for direct modulation of the human microbiome in health and disease.
Clinical marker
A multi-locus genetic risk score study based on a combination of 27 loci, including the ABO gene, identified individuals at increased risk for both incident and recurrent coronary artery disease events, as well as an enhanced clinical benefit from statin therapy. The study was based on a community cohort study (the Malmo Diet and Cancer study) and four additional randomized controlled trials of primary prevention cohorts (JUPITER and ASCOT) and secondary prevention cohorts (CARE and PROVE IT-TIMI 22).
Alteration of ABO antigens for transfusion
In April 2007, an international team of researchers announced in the journal ''
Nature Biotechnology
''Nature Biotechnology'' is a monthly peer-reviewed scientific journal published by Nature Portfolio. The chief editor heads an in-house team of editors. The focus of the journal is biotechnology including research results and the commercial busi ...
'' an inexpensive and efficient way to convert types A, B, and AB blood into type O. This is done by using
glycosidase
Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (c ...
enzymes from specific bacteria to strip the blood group antigens from
red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s. The removal of A and B antigens still does not address the problem of the
Rh blood group antigen on the blood cells of Rh positive individuals, and so blood from Rh negative donors must be used. The sort of blood is named "enzyme converted to O" (ECO) blood. Patient trials will be conducted before the method can be relied on in live situations. One such Phase II trial was done on B-to-O blood in 2002.
Another approach to the blood antigen problem is the manufacture of
artificial blood
A blood substitute (also called artificial blood or blood surrogate) is a substance used to mimic and fulfill some functions of biological blood. It aims to provide an alternative to blood transfusion, which is transferring blood or blood-based ...
, which could act as a substitute in emergencies.
Pseudoscience
During the 1930s, connecting
blood groups to personality types became popular in Japan and other areas of the world. Studies of this association have yet to confirm its existence definitively.
Other popular but unsupported ideas include the use of a
blood type diet
The blood type diets are fad diets advocated by several authors, the most prominent of whom is Peter J. D'Adamo. These diets are based on the notion that blood type, according to the ABO blood group system, is the most important factor in determin ...
, claims that group A causes severe
hangover
A hangover is the experience of various unpleasant physiological and psychological effects usually following the consumption of alcohol, such as wine, beer, and liquor. Hangovers can last for several hours or for more than 24 hours. Typical sympto ...
s, group O is associated with perfect teeth, and those with blood group A2 have the highest
IQs. Scientific evidence in support of these concepts is limited at best.
See also
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Secretor status – secretion of ABO antigens in body fluids
References
Further reading
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*
External links
ABOat
BGMUT Blood Group Antigen Gene Mutation Database at
NCBI
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...
,
NIH
The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...
Encyclopædia Britannica, ABO blood group system
{{Authority control
Blood antigen systems
Transfusion medicine
Antigenic determinant
Hematopathology
Glycoproteins
Serology
Genes on human chromosome 9