Editing Blood type (section)

===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>