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Medical Term:

blood group

Pronunciation: blŭd grūp


  1. A system of antigens under the control of closely linked allelic loci on the surface of the erythrocyte. Because of the antigenic differences existing between individuals, blood groups are significant in blood transfusions, maternal-fetal incompatibilities (hemolytic disease of the newborn), tissue and organ transplantation, disputed paternity cases, and in genetic and anthropologic studies; certain blood groups may be related to susceptibility or resistance to certain diseases. Often used as synonymous with blood type. See Blood Groups Appendix for individual groups: ABO, Auberger, Diego, Duffy, I, Kell, Kidd, Lewis, Lutheran, MNSs, P, Rh, Sutter, Xg, and the low-frequency and high-frequency blood groups.
  2. The classification of blood samples by means of laboratory tests of their agglutination reactions with respect to one or more blood groups. In general, a suspension of erythrocytes to be tested is exposed to a known specific antiserum; agglutination of the erythrocytes indicates that they possess the antigen for which the antiserum is specific. Certain antisera require special testing conditions.
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