Diego antigen system
Encyclopedia
The Diego Antigen System comprises 21 rare blood factors, any of which is carried on the band 3 protein
, coded for by the gene SLC4A1 (Solute carrier family
4, Anion exchanger, member 1), located on human chromosome 17
. The band 3 protein functions in the transport of chlorine
ions and carbonate
. The resulting factor of each SLC4A1 allele is classified as a separate blood group
.
Diego antigens are only found (or in some cases, only not found) in populations of Aboriginal Americans (in both North and South America) and the Mongolic peoples of East, Southeast, North-Central and Northeast Asia. Incidence of the factors is not diminished in ethnically mixed populations. Indeed, the first two Diego factors were found in people of mixed European and Aboriginal American ancestry.
s were thought to be separate systems until 1992, when it was realised they were part of one system. The labeling of individual factors, however, has not changed, with the former Wright factors still signed 'Wr' while the rest of the Diego factors are signed 'Di'.
The first component of the system, Diego a, was discovered in Venezuela in 1955, when one Sra. (Mrs.) Diego gave birth to a child who died from Hemolytic disease of the newborn
. Rh system mismatch was initially suspected, but Mr. and Mrs. Diego were both RhD positive so it could not have been that. Mr. Diego, however, had some aboriginal South American ancestry that Mrs. Diego did not, and that fact ultimately led to the discovery of Diego a.
Diego b was discovered under similar circumstances in Mexico
in 1967. In this case, however, the problem was not the father being Dib+ but the mother was Dib-. The occurrence of Dib- practically does not exist in most ethnic populations, and is exceptionally rare (about 0.001%) even among populations in which Dia+ is found.
In 1992, the two Wright antigens, Wra and Wrb, were reclassified as part of the Diego system, which now contains 21 known factors.
The two most important factors in the system are Dia/Dib and Wra/Wrb ('Di' for "Diego" and 'Wr' for "Wright"). Each pair contains a low-incidence antigen and an antithetical high-incidence determinant, respectively. Most ethnic populations of the world, for example, present as Dia-/Dib+.
In particular, Dia+ has an insignificant occurrence (0.01%) in populations of Indo-European, West and Southwest Asian, African, and Australasian ancestry. The occurrence is comparatively significant in Southeast, East, North-Central and Northeast Asian, presenting in 5% to 15% of these populations; and more significant in Aboriginal North and South American peoples, where occurrence ranges between 0% and 36%, with higher percentages of occurrence more often found in South American aboriginal populations than North American. There is, however, no apparent pattern to Dia+ distribution in either American continent, nor in Asia.
One constant is that Dia+ may be found in any person with ancestry from one of the Mongolic-Aboriginal American groups in which the factor occurs. Thus, when an American of Polish extraction presented as Dia+, research of his ethno-cultural ancestry traced his family to southwestern Poland and a population of mixed Polish
and Tatar ancestry. He inherited the gene for the Diego A factor through the latter side of his ancestry. The cultural distribution of the blood group lends it some importance to the science of anthropology
.
Band 3
Anion Exchanger 1 or Band 3 is a phylogenetically preserved transport protein responsible for mediating the exchange of chloride for bicarbonate across a plasma membrane. Functionally similar members of the AE clade are AE2 and AE3.It is ubiquitous throughout the vertebrates...
, coded for by the gene SLC4A1 (Solute carrier family
Solute carrier family
The solute carrier group of membrane transport proteins include over 300 members organized into 51 families. The SLC gene nomenclature system was originally proposed by the Human Genome Organization and is the basis for the official HUGO names of the genes that encode these transporters...
4, Anion exchanger, member 1), located on human chromosome 17
Chromosome 17 (human)
125px|rightChromosome 17 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 17 spans more than 81 million base pairs and represents between 2.5 and 3 % of the total DNA in cells.Identifying genes on each chromosome is an active area of...
. The band 3 protein functions in the transport of chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
ions and carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
. The resulting factor of each SLC4A1 allele is classified as a separate blood group
Human blood group systems
The International Society of Blood Transfusion currently recognises 30 major blood group systems . Thus, in addition to the ABO antigens and Rhesus antigens, many other antigens are expressed on the red blood cell surface membrane...
.
Diego antigens are only found (or in some cases, only not found) in populations of Aboriginal Americans (in both North and South America) and the Mongolic peoples of East, Southeast, North-Central and Northeast Asia. Incidence of the factors is not diminished in ethnically mixed populations. Indeed, the first two Diego factors were found in people of mixed European and Aboriginal American ancestry.
History and occurrence
The Diego and Wright antigenAntigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
s were thought to be separate systems until 1992, when it was realised they were part of one system. The labeling of individual factors, however, has not changed, with the former Wright factors still signed 'Wr' while the rest of the Diego factors are signed 'Di'.
The first component of the system, Diego a, was discovered in Venezuela in 1955, when one Sra. (Mrs.) Diego gave birth to a child who died from Hemolytic disease of the newborn
Hemolytic disease of the newborn
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus, when the IgG molecules produced by the mother pass through the placenta...
. Rh system mismatch was initially suspected, but Mr. and Mrs. Diego were both RhD positive so it could not have been that. Mr. Diego, however, had some aboriginal South American ancestry that Mrs. Diego did not, and that fact ultimately led to the discovery of Diego a.
Diego b was discovered under similar circumstances in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
in 1967. In this case, however, the problem was not the father being Dib+ but the mother was Dib-. The occurrence of Dib- practically does not exist in most ethnic populations, and is exceptionally rare (about 0.001%) even among populations in which Dia+ is found.
In 1992, the two Wright antigens, Wra and Wrb, were reclassified as part of the Diego system, which now contains 21 known factors.
The two most important factors in the system are Dia/Dib and Wra/Wrb ('Di' for "Diego" and 'Wr' for "Wright"). Each pair contains a low-incidence antigen and an antithetical high-incidence determinant, respectively. Most ethnic populations of the world, for example, present as Dia-/Dib+.
In particular, Dia+ has an insignificant occurrence (0.01%) in populations of Indo-European, West and Southwest Asian, African, and Australasian ancestry. The occurrence is comparatively significant in Southeast, East, North-Central and Northeast Asian, presenting in 5% to 15% of these populations; and more significant in Aboriginal North and South American peoples, where occurrence ranges between 0% and 36%, with higher percentages of occurrence more often found in South American aboriginal populations than North American. There is, however, no apparent pattern to Dia+ distribution in either American continent, nor in Asia.
One constant is that Dia+ may be found in any person with ancestry from one of the Mongolic-Aboriginal American groups in which the factor occurs. Thus, when an American of Polish extraction presented as Dia+, research of his ethno-cultural ancestry traced his family to southwestern Poland and a population of mixed Polish
Poles
thumb|right|180px|The state flag of [[Poland]] as used by Polish government and diplomatic authoritiesThe Polish people, or Poles , are a nation indigenous to Poland. They are united by the Polish language, which belongs to the historical Lechitic subgroup of West Slavic languages of Central Europe...
and Tatar ancestry. He inherited the gene for the Diego A factor through the latter side of his ancestry. The cultural distribution of the blood group lends it some importance to the science of anthropology
Anthropology
Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...
.