In 1940 , Land Steiner & wiener found Rh antigen. Multiple Allele theory was put forward by Wiener. According to this theory Rh blood groups are determined by a series of multiple alleles designated as Ri, R2, R’, R’1 ,Rr or R2, Ro, Ry and ‘r’ etc.
Later Fisher put forward the’ Gene Complex Theory’. This theory reveals that the three pairs of closely linked genes determine the various Rh blood groups. These genes are so closely linked and inherited as a block and are called ‘pseudo alleles. These three pairs of are CPEI cde which can form eight possible combinations as follows. Recent investigations supposed the Fishers Gene complex theory.
Each haploid combination of these three genes is inherited together as a single gene out of these eight combinations. The most common complexes are only three. These are C D e (R i’ cC E (R2) and cd e (r).
The dominant genes C D E determine the production of protein C, protein D and protein E. Depending upon the agglutination reactions with these proteins four types of antisera have been identified.
(i) antisera . D, containing antibody against protein - I), antl-D.
(ii) antisera -c, contains antibody against protein C, -anti -c. It reacts with Rh - groups.
(iii) antisera -E, contains antibody against protein E.
(iv) antisera -C, cntains antibodies against proteins C and D.