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The Rh(D) antigen is [[Inheritance|inherited]] on the first [[chromosome]]: Rh pos is dominant and Rh neg is recessive. The [[gene]] codes for a polypeptide on the red cell membrane. Rh neg individuals - those with a recessive DD (that is, dd) genotype - do not produce this antigen, and thus may be sensitized to Rh pos blood.

The Rh(D) antigen is [[Inheritance|inherited]] on the first [[chromosome]]: Rh pos is dominant and Rh neg is recessive. The [[gene]] codes for a polypeptide on the red cell membrane. Rh neg individuals - those with a recessive DD (that is, dd) genotype - do not produce this antigen, and thus may be sensitized to Rh pos blood.

The principal discoveries were made in 1937 by Karl Landsteiner and Alexander S. Wiener<ref>Landsteiner K, Wiener AS. ''An agglutinable factor in human blood recognized by immune sera for rhesus blood''. Proc Soc Exp Biol Med 1940;43:223-224</ref>. Experiments in which rabbits immunized with Rhesus monkey red cells showed an antibody that results in clumping of the red blood cells of many humans. Dr. Phillip Levine working at the Newark Beth Israel Hospital linked the Rh factor and the incidence of erythroblastosis fetalis (wherein maternal red cells attack the foetal red cells); Wiener realized that adverse reactions from transfusions were also resulting from the Rh factor.  

The principal discoveries were made in 1937 by Karl Landsteiner and Alexander S. Wiener.<ref>Landsteiner K, Wiener AS. ''An agglutinable factor in human blood recognized by immune sera for rhesus blood''. Proc Soc Exp Biol Med 1940;43:223-224</ref> Experiments in which rabbits immunized with Rhesus monkey red cells showed an antibody that results in clumping of the red blood cells of many humans. Dr. Phillip Levine working at the Newark Beth Israel Hospital linked the Rh factor and the incidence of erythroblastosis fetalis (wherein maternal red cells attack the foetal red cells); Wiener realized that adverse reactions from transfusions were also resulting from the Rh factor.  

==Blood group differences by ethnic origin==

==Blood group differences by ethnic origin==

The ethnic origin of people can be a good, but not certain, indicator of their blood type<ref>Dean, L., ''[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=rbcantigen.chapter.ch2 Blood Group and Red Cell Antigens]'', Chapter 2, National Institute for Health: National Centre for Biotechnical Information, accessed 1 January 2008</ref>.

The ethnic origin of people can be a good, but not certain, indicator of their blood type.<ref>Dean, L., ''[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=rbcantigen.chapter.ch2 Blood Group and Red Cell Antigens]'', Chapter 2, National Institute for Health: National Centre for Biotechnical Information, accessed 1 January 2008</ref>  

For instance:

For instance:

* Asians are about 98% Rh D pos.

* Asians are about 98% Rh D pos.

==See Also==

==See also==

[[Blood Type Diet]]

[[Blood Type Diet]]