Tay lái thuận lai như vậy có thể loại như D tích cực bởi vì trình tự D bình thường mà là hiện tại, trong khi cùng một lúc một kháng thể chống lại tích cực các tế bào bình thường D-đỏ tương ứng với một phần của chuỗi polypeptide D mà họ thiếu. Kháng thể này sẽ có tính đặc anti-D, do đó các cá nhân sẽ xuất hiện là D dương tính | CHAPTER 5 with such hybrid RHD may type as D positive because of the normal D sequence that is present while at the same time making an antibody against normal D-positive red cells corresponding to the part of the D polypeptide that they lack. This antibody will have the specificity anti-D so the individuals will appear to be D positive with allo-anti-D. In the first study that recognized the existence of missing parts of D antigen the red cells were described as Rh variants originally three RhA RhB and RhC were defined Unger and Wiener 1959 and a fourth RhD was soon added Sacks et al. 1959 . The collection of original sera defining these four variants is no longer available. In the second classification D-positive subjects who have made anti-D were divided into seven categories Tippett and Sanger 1962 1977 Lomas et al. 1986 . Antibodies made by different members of the same category may not be identical but by definition red cells and sera of members of the same category are mutually compatible. Several categories are characterized by having a particular low-incidence antigen in addition to lacking certain parts of D. Classification by categories is likely to fall out of use eventually because the sera used originally are scarce and rather weak reviewed by Tippett et al. 1996 . A third classification became possible when large numbers of monoclonal anti-D reagents became available. In this classification different partial D antigens are distinguished by their pattern of reactivity with a large panel of monoclonal anti-Ds and allo-anti-D made by D-positive individuals is not employed. Using this approach 30 different patterns of reactivity were observed Table . This dramatic increase in the number of partial D phenotypes is a reflection of the experimental method . use of monoclonal antibodies which allows detection of partial D in D-positive individuals who have not made allo-anti-D. Partial E There is evidence of the existence of several variants of E. Of
