Editing Blood type (section)

==Blood group systems==
{{main|Human blood group systems}}

A complete blood type would describe each of the 47 blood groups, and an individual's blood type is one of many possible combinations of blood-group antigens.<ref name=":2" /> Almost always, an individual has the same blood group for life, but very rarely an individual's blood type changes through addition or suppression of an antigen in [[infection]], [[malignancy]], or [[autoimmune disease]].<ref name=":2">{{harvnb|Dean|2005|loc=[https://www.ncbi.nlm.nih.gov/books/n/rbcantigen/ch05ABO/ The ABO blood group] "... A number of illnesses may alter a person's ABO phenotype ..."}}</ref><ref>{{cite journal |vauthors=Stayboldt C, Rearden A, Lane TA |title=B antigen acquired by normal A1 red cells exposed to a patient's serum |journal=Transfusion |volume=27 |issue=1 |pages=41–4 |year=1987 |pmid=3810822 |doi=10.1046/j.1537-2995.1987.27187121471.x }}</ref><ref>{{cite journal |vauthors=Matsushita S, Imamura T, Mizuta T, Hanada M |title=Acquired B antigen and polyagglutination in a patient with gastric cancer |journal=The Japanese Journal of Surgery |volume=13 |issue=6 |pages=540–2 |date=November 1983 |pmid=6672386 |doi=10.1007/BF02469500 }}</ref><ref>{{cite journal |last1=Kremer Hovinga |first1=Idske CL |last2=Koopmans |first2=Marije |last3=de Heer |first3=Emile |last4=Bruijn |first4=Jan A |last5=Bajema |first5=Ingeborg M |title=Change in blood group in systemic lupus erythematosus |journal=The Lancet |date=January 2007 |volume=369 |issue=9557 |pages=186–187 |doi=10.1016/S0140-6736(07)60099-3 |pmid=17240276 |doi-access=free }}</ref> Another more common cause of blood type change is a [[bone marrow transplant]]. Bone-marrow transplants are performed for many [[leukemias]] and [[lymphomas]], among other diseases. If a person receives bone marrow from someone of a different ABO type (e.g., a type O patient receives a type A bone marrow), the patient's blood type should eventually become the donor's type, as the patient's [[hematopoietic stem cell]]s (HSCs) are destroyed, either by ablation of the bone marrow or by the donor's T-cells. Once all the patient's original red blood cells have died, they will have been fully replaced by new cells derived from the donor HSCs. Provided the donor had a different ABO type, the new cells' surface antigens will be different from those on the surface of the patient's original red blood cells.<ref name="pmid27022317">{{cite journal |vauthors=Worel N |title=ABO-Mismatched Allogeneic Hematopoietic Stem Cell Transplantation |journal=Transfus Med Hemother |volume=43 |issue=1 |pages=3–12 |date=January 2016 |pmid=27022317 |doi=10.1159/000441507 |pmc=4797460 |url=}}</ref>

Some blood types are associated with inheritance of other diseases; for example, the [[Kell blood group system|Kell antigen]] is sometimes associated with [[McLeod syndrome]].<ref><!--
 -->{{cite journal |author1=Chown B. |author2=Lewis M. |author3=Kaita K. |title=A new Kell blood-group phenotype |journal=Nature |volume=180 |issue=4588 |page=711 |date=October 1957 |pmid=13477267 |doi=10.1038/180711a0|bibcode=1957Natur.180..711C |doi-access=free }}</ref> Certain blood types may affect susceptibility to infections, such as the resistance to specific [[malaria]] species seen in individuals lacking the [[Duffy antigen]].<ref><!--
 -->{{cite journal |doi=10.1056/NEJM197608052950602 |vauthors=Miller LH, Mason SJ, Clyde DF, McGinniss MH |title=The resistance factor to Plasmodium vivax in blacks. The Duffy-blood-group genotype, FyFy |journal=The New England Journal of Medicine |volume=295 |issue=6 |pages=302–4 |date=August 1976 |pmid=778616}}</ref><!--
 --> The Duffy antigen, presumably as a result of [[natural selection]], is less common in population groups from areas having a high incidence of malaria.<ref>{{cite journal |author=Kwiatkowski DP |title=How Malaria Has Affected the Human Genome and What Human Genetics Can Teach Us about Malaria |journal=American Journal of Human Genetics |volume=77 |issue=2 |pages=171–92 |date=August 2005 |pmid=16001361 |pmc=1224522 |doi=10.1086/432519 |quote=The different geographic distributions of α thalassemia, G6PD deficiency, ovalocytosis, and the Duffy-negative blood group are further examples of the general principle that different populations have evolved different genetic variants to protect against malaria}}</ref>  

===ABO blood group system===
[[Image:ABO blood group diagram.svg|right|thumb|350px|''ABO blood group system'': diagram showing the carbohydrate chains that determine the ABO blood group]]
[[Image:Punnett_square_blood_types.svg|right|thumb|350px|Simplified [[Punnett square]] of the possible genotypes and phenotypes of children given genotypes and phenotypes of their mother (rows) and father (columns) shaded by phenotype]]
{{Main|ABO blood group system}}

The ABO blood group system involves two antigens and two antibodies found in human blood. The two antigens are antigen A and B. The two antibodies are A and B. The antigens are present on the red blood cells and the antibodies in the [[serum (blood)|serum]]. Regarding the antigen property of the blood all human beings can be classified into four groups: those with antigen A (group A), those with antigen B (group B), those with both antigen A and B (group AB) and those with neither antigen (group O). The antibodies present together with the antigens are found as follows:{{citation needed|date=November 2021}}
# Antigen A with antibody B
# Antigen B with antibody A
# Antigen AB with neither antibody A nor B
# Antigen null (group O) with both antibodies A and B

There is an [[Agglutination (biology)|agglutination]] reaction between similar antigen and antibody (for example, antigen A agglutinates the antibody A and antigen B agglutinates the antibody B). Thus, transfusion can be considered safe as long as the serum of the recipient does not contain antibodies for the blood cell antigens of the donor.{{citation needed|date=November 2021}}

The ABO system is the most important blood-group system in human-blood transfusion. The associated anti-A and anti-B antibodies are usually [[immunoglobulin M]], abbreviated [[IgM]], antibodies. It has been hypothesized that ABO IgM [[antibodies]] are produced in the first years of life by sensitization to environmental substances such as food, [[bacteria]], and [[virus]]es.<ref>{{cite web|title=Position statement: Red blood cell transfusion in newborn infants |url=https://www.cps.ca/en/documents/position/red-blood-cell-transfusion-newborn-infants |publisher=Canadian Pediatric Society |archive-url=https://web.archive.org/web/20180519120449/https://www.cps.ca/en/documents/position/red-blood-cell-transfusion-newborn-infants |archive-date=19 May 2018 |date=April 14, 2014}}</ref> The original terminology used by [[Karl Landsteiner]] in 1901 for the classification was A/B/C; in later publications "C" became "O".<ref name=Oor0>{{cite journal |last1=Schmidt |first1=P. |last2=Okroi |first2=M. |title=Also sprach Landsteiner – Blood Group 'O' or Blood Group 'NULL' |journal=Transfusion Medicine and Hemotherapy |date=2001 |volume=28 |issue=4 |pages=206–208 |doi=10.1159/000050239 }}</ref> Type O is often called ''0'' (''zero'', or ''null'') in other languages.<ref name="Oor0"/><ref>{{cite web |url=https://www.bloddonor.dk/fileadmin/Fil_Arkiv/PDF_filer/Andre/Your_Blood__June_2006.pdf |title=Your blood&nbsp;– a textbook about blood and blood donation |access-date=2008-07-15 |page=63 |archive-url = https://web.archive.org/web/20080626184746/https://www.bloddonor.dk/fileadmin/Fil_Arkiv/PDF_filer/Andre/Your_Blood__June_2006.pdf |archive-date = June 26, 2008}}</ref>
{| class="wikitable plainrowheaders" style="text-align:center;"
|+Phenotype and genotype of blood types
|-
! scope="col"|[[Phenotype]]
! scope="col"|[[Allele|Alleles]]
|-
!scope="row"| A
| ABO*A1.01
|-
!scope="row"| B
| ABO*B1.01
|-
!scope="row"| AB
| ABO*A1.01, ABO*B1.01
|-
!scope="row"| O
| Two nonfunctional ABO genes
|}

===Rh blood group system===
{{Main|Rh blood group system}}
The Rh system (Rh meaning ''[[Rh blood group system|Rhesus]]'') is the second most significant blood-group system in human-blood transfusion with currently 50 antigens. The most significant Rh antigen is the D antigen, because it is the most likely to provoke an immune system response of the five main Rh antigens. It is common for D-negative individuals not to have any anti-D IgG or IgM antibodies, because anti-D antibodies are not usually produced by sensitization against environmental substances. However, D-negative individuals can produce [[Immunoglobulin G|IgG]] anti-D antibodies following a sensitizing event: possibly a fetomaternal transfusion of blood from a fetus in pregnancy or occasionally a blood transfusion with D positive [[Red blood cell|RBC]]s.<ref name="Talaro, Kathleen P. 2005 510–1">{{cite book|author=Talaro, Kathleen P.|title=Foundations in microbiology|url=https://archive.org/details/foundationsinmic00kath|url-access=registration|publisher=McGraw-Hill|location=New York|year=2005|pages=[https://archive.org/details/foundationsinmic00kath/page/510 510–1]|isbn=0-07-111203-0 |edition=5th}}</ref><ref>{{cite journal |last1=Moise |first1=Kenneth J. |title=Management of Rhesus Alloimmunization in Pregnancy |journal=Obstetrics & Gynecology |date=July 2008 |volume=112 |issue=1 |pages=164–176 |doi=10.1097/AOG.0b013e31817d453c |pmid=18591322 }}</ref> Rh negative blood types are much less common in Asian populations (0.3%) than they are in European populations (15%).<ref name="Rh group and its origin">{{cite web|url=https://hospital.kingnet.com.tw/activity/blood/html/a.html|title=Rh血型的由來|publisher=Hospital.kingnet.com.tw|access-date=2010-08-01|archive-date=2009-12-11|archive-url=https://web.archive.org/web/20091211201528/http://hospital.kingnet.com.tw/activity/blood/html/a.html|url-status=live}}</ref>

The presence or absence of the Rh(D) antigen is signified by the + or − sign, so that, for example, the A− group is ABO type A and does not have the Rh (D) antigen.<ref>{{cite book |doi=10.1016/B978-075067572-7.50033-3 |chapter=Bleeding, Hemostasis, and Transfusion Medicine |title=Cardiothoracic Critical Care |date=2007 |last1=Levy |first1=Jerrold H. |last2=McKee |first2=Andrew |pages=437–460 |isbn=978-0-7506-7572-7 }}</ref>

===ABO and Rh distribution by country===
{{main|Blood type distribution by country}}

As with many other genetic traits, the distribution of ABO and Rh blood groups varies significantly between populations.{{citation needed|date=November 2021}}<ref>{{Cite journal |last1=Mohamud |first1=Mohamed Hayir Tahill |last2=Aweis |first2=Abdullah Dahir H |last3=Adam |first3=Abdiwahab Sheikh Elmi |last4=Mohamed |first4=Farhia Abdullahi |last5=Fidow |first5=Safia Qasim |last6=Mohamed |first6=Lul Mohamud |date=30 January 2022 |title=Distribution and Frequency of ABO and Rhesus (D) Blood Groups in Somalia: A Retrospective Study on Students of Jazeera University, Mogadishu-Somalia |journal=BioMed Research International |volume=2022 |issue=7981325|pages=1–5 |doi=10.1155/2022/7981325 |pmid=35136827 |pmc=8818412 |doi-access=free }}</ref> While theories are still debated in the scientific community as to why blood types vary geographically and why they emerged in the first place, evidence suggests that the evolution of blood types may be driven by genetic selection for those types whose antigens confer resistance to particular diseases in certain regions – such as the prevalence of blood type O in malaria-endemic countries where individuals of blood type O exhibit the highest rates of survival.<ref>{{Cite journal |last1=Cserti |first1=Christine M. |last2=Dzik |first2=Walter H. |date=1 October 2007 |title=The ABO blood group system and Plasmodium falciparum malaria |journal=American Society of Hematology |volume=110 |issue=7|pages=2250–2258 |doi=10.1182/blood-2007-03-077602 |pmid=17502454 |doi-access=free }}</ref>

===Other blood group systems===
{{Main|Human blood group systems}}
As of October 2024, 47 blood-group systems have been identified by the International Society for Blood Transfusion in addition to the ABO and Rh systems.<ref name=":1" /> Thus, in addition to the ABO antigens and Rh antigens, many other antigens are expressed on the RBC surface membrane. For example, an individual can be AB, D positive, and at the same time M and N positive ([[MNS antigen system|MNS system]]), K positive ([[Kell antigen system|Kell system]]), Le<sup>a</sup> or Le<sup>b</sup> negative ([[Lewis antigen system|Lewis system]]). Many of the blood group systems were named after the patients in whom the corresponding antibodies were initially encountered. Blood group systems other than ABO and Rh pose a potential, yet relatively low, risk of complications upon mixing of blood from different people.<ref name="GoodellUhl2010">{{cite journal |last1=Goodell |first1=Pamela P. |last2=Uhl |first2=Lynne |last3=Mohammed |first3=Monique |last4=Powers |first4=Amy A. |title=Risk of Hemolytic Transfusion Reactions Following Emergency-Release RBC Transfusion |journal=American Journal of Clinical Pathology |date=August 2010 |volume=134 |issue=2 |pages=202–206 |doi=10.1309/AJCP9OFJN7FLTXDB |pmid=20660321 |doi-access=free }}</ref>

Following is a comparison of clinically relevant characteristics of antibodies against the main human blood group systems:<ref name="Mais 2014">{{cite book | last=Mais | first=Daniel | title=Quick compendium of clinical pathology | publisher=American Society for Clinical Pathology Press | publication-place=United States | year=2014 | isbn=978-0-89189-615-9 | oclc=895712380 | page=}}{{pn|date=November 2024}}</ref>
{|class="wikitable"
!  !! [[ABO blood group system|ABO]] !! [[Rh blood group system|Rh]] !! [[Kell antigen system|Kell]] !! [[Duffy antigen system|Duffy]] !! [[Kidd antigen system|Kidd]]
|-
! Naturally occurring
| Yes || No || No || No || No
|-
! Most common in immediate hemolytic transfusion reactions
|  A|| ||  Yes||  Fy<sup>a</sup>||  Jk<sup>a</sup>
|-
! Most common in delayed hemolytic transfusion reactions
| ||  E, D, C|| || ||  Jk<sup>a</sup>
|-
! Most common in [[hemolytic disease of the newborn]]
|  Yes||  D, C||  Yes|| ||
|-
! Commonly produce intravascular hemolysis
|  Yes|| || || ||  Yes
|}