Rhesus Isoimmunization Mandakini Parihar
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Rh Blood Group SystemCHAPTER 1

Malhotra Maya Parihar
 
INTRODUCTION
Landsteiner “the father of blood groups “discovered the ABO blood groups in 1901 and named the first two blood factors after the first two letters of the alphabet.1 Karl Landsteiner made many important contributions to immunology which are overshadowed by the Nobel prize for his discovery of ABO groups. In 1939 Levine and Stetson2 had described an atypical antibody which occurred in the serum of a woman delivered of a stillborn fetus with erythroblastosis fetalis. Shortly after delivery she had required a blood transfusion and was given her husband's blood which caused a hemolytic transfusion reaction. Levine and Stetson postulated that the antibody had arisen as the result of immunization of the mother by a fetal antigen which had been inherited from the father.
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Prof. Karl Landsteiner
In 1940 Landsteiner and Wiener reported the discovery of a human blood factor which they called “rhesus” or Rh.3 They immunized guinea pigs and rabbits with blood from the Macacus rhesus monkey and thereby obtained an antiserum which, after suitable absorption, agglutinated not only the red cells of the rhesus monkey but also approximately 85 percent of a panel of blood samples from the white population of New York. They used it to type as “Rh positive” those whose red cells were agglutinated by the new antibody and as “Rh negative” those whose red cells were not so agglutinated. The antibody responsible they called “anti-Rh”. Family studies showed that, the Rh factor was segregating independently of A and B.2
Initially it was thought that the human antibodies and the animal antibodies identified a common factor, Rh on the surface of rhesus and human RBCs. However, it was soon realized that both antibodies were different. Later this heteroantibody was named LW (Landsteiner and Wiener), because it was shown to be different from that found in humans. The human alloantibody described by Levine was called Rh for the rhesus monkey, although it was the anti-LW that was produced in the rhesus monkeys and the Rh antibody (described by Levine-Stetson and later renamed anti-D4) that was produced in the humans.
Subsequently, Levine and his coworkers in 1941,57 reported in a series of papers results of their work: which showed that not only could an Rh- negative mother become immunized to an Rh-positive fetus in utero but also that the antibody could then traverse the placenta and give rise to “erythroblastosis fetalis” or, as it is now called, “hemolytic disease of the newborn” (HDN). Moreover, they showed that these antibodies were ‘warm’ antibodies reacting more strongly at 37°C than at lower temperatures. The Rh factor was antigenic in man and the anti-Rh antibodies which were found as a result of immunization could destroy incompatible blood in vivo.
The Rh blood group system is the most polymorphic and immunogenic of the human blood groups, consisting of at least 45 independent antigens and, next to ABO, is the most clinically significant in transfusion medicine. The ability to clone complementary DNA (cDNA) and sequence genes encoding the Rh proteins has led to an understanding of the molecular bases associated with some of the Rh antigens. Serologic detection of polymorphic blood group antigens and of phenotypes provides a valuable source of appropriate blood samples for study at the molecular level. Several nomenclatures have been used to describe antigens, proteins, and genes in the Rh system.
 
Various Rh Antigens and Theory of Inheritance
 
Fisher-Race Theory
Fisher and Race8 formulated that the Rh system is controlled by three pairs of allelic genes, Cc, Dd and Ee on chromosome 1. Eight possible haplotypes arise from these three pairs of closely linked genes and they are shown in Table 1.1. The common Rh antigens: D, C or c, and E or e, were originally written in alphabetical order (CDE) but later, when it was recognized that C and E antigens are inherited en bloc, the order was changed to DCE. D negative individuals were found to have only the gene determining C c E or e with no allelic counterpart of D.9 The antibodies are anti-D, Anti-C, anti-c, Anti-E and anti-e.
However, an antibody with the predicted reactions for ‘d’ has not been discovered, and ‘d’ is now regarded as being ‘silent allele’ (amorph) and 3is used to indicate the D-negative phenotype. Therefore no mention in Table 1.1.
 
Theory of Wiener
Wiener10 favored the concept of one gene instead of three closely linked ones. He postulated that a gene gives rise to an agglutinogen on the red cell surface and that this in turn possesses a number of blood factors. For example, the gene R1 (Table 1.1) gives rise to the agglutinogen Rh1 which possesses the three blood factors Rh0, rh' and hr”. The blood factor hr refers to the Fisher compound antigen ce. Wiener adopted the convention of italics for ‘genes and genotypes’, regular type for ‘agglutinogens and phenotypes’ and bold-face for “blood factors and corresponding antibodies”.
Table 1.1   Antigens and blood factors
Notation gene
Wiener notation
Agglutinogen
Blood factors
Antigens
CDe
R1
Rh1
Rh0 rh' hr”
D C E
cDE
R2
Rh2
Rh0 rh” hr'
D c E
cDe
R0
Rh0
Rh0 hr' hr” hr
D c e
CDE
Rz
Rhz
Rh0 rh' rh”
D C E
Cde
r'
rh'
rh' hr”
C e
cdE
r”
rh”
rh” hr'
c E
CdE
ry
rhy
rh' rh”
C E
cde
r
rh
hr' hr” hr
c e
Table 1.1 shows the antigens and blood factors formed by the eight gene complexes. It is of course an over-simplification, as the complexes are haplotypes and every individual will have two of them making up his genotype, one inherited from each parent. The uppercase “R” is used when the D antigen is expressed, lowercase “r” when it is not. This notation has practical value in transfusion medicine as a means to communicate the Rh phenotype of a patient or donor. Rare deletion phenotypes use dashes in the notation to indicate a lack of antithetical antigens, e.g. Dc_. RBC's lack E and e antigens, and D_ _ RBC's lack C, c, E, and e antigens. RBC's with the Rhnull phenotype do not express any of the Rh antigens.
 
Numerical Terminology
In 1962 Rosenfield et al11 suggested a numerical nomenclature for Rh system which was intended to allow investigators to report serologic findings without necessarily including genetic interpretations, e.g. D or Rh0 became Rh1, C or rh' became Rh2, etc. and D+c+e- became (Rh1,4–5), etc.
Rosenfield et al 12 allocated Rh1 to Rh 25 and other investigators have since allocated Rh 26 to Rh 52.13,14 However this method is not user friendly.4
 
ISBT-Numeric Terminology
The ISBT working committee proposed assigning numbers to specificities as standard alternatives to current alphabetical names in those circumstances where numbers are necessary as in some computer systems.1517 The working committee party suggested using uppercase letters and Arabic numbers for system and antigen codes. Each system, collection or series of antigens is given a number (e.g. ABO system=001 and Rh +004) and each antigen within the system is given a number (e.g. A = 001, B= 002 and in the Rh system D=001, C=002, E=003, etc). Thus for the computer D, C and E are 004001, 004002 and 004003 respectively (Tables 1.2 and 1.3).18
Table 1.2   Rh blood group system antigens with the ISBT symbols
D (RH1)
G(RH12)
Rh29(RH29)
Rh41(RH41)
C (RH2)
Hr0(RH17)
Goa(RH30)
Rh42(RH42)
E (RH3)
Hr(RH18)
hr3(RH31)
Craw(RH43)
c (RH4)
hrs(RH19)
Rh32(RH32)
Nou(RH44)
e (RH5)
VS(RH20)
Rh33(RH33)
Riv(RH45)
f (RH6)
CG(RH21)
HrB(RH34)
Sec(RH46)
Ce (RH7)
CE(RH22)
Rh35(RH35)
Dav(RH47)
Cw (RH8)
Dw(RH23)
Bea(RH36)
JAL(RH48)
Cx (RH9)
c-like(RH26)
Evans(RH37)
STEM(RH49)
V (RH10)
cE(RH27)
Rh39(RH39)
FPTT(RH50)
Ew (RH11)
hrH(RH28)
Tar(RH40)
MAR(RH51)
BARC(RH52)
Table 1.3   Blood group systems
System name
System symbol
Traditional/ISBT
ISBT number
Traditional
ISBT
ABO
001
ABO
ABO
Rh
004
Rh
RH
Fisher's original theory (DCE terminology) is recommended by WHO Expert Committee in interest of simplicity and conformity. Wiener notation is still used especially for describing phenotypes. Some numbers, e.g. Rh29 (total Rh) are used for the lack of more convenient alternatives.
 
Rh Complex
The “Rh proteins” carry Rh antigens but are only expressed on the erythrocyte surface if RhAG is also present. The amino acid sequence homology (approximately 40 percent) of the Rh and RhAG proteins indicates an ancestral relationship, and collectively they are referred to as the “Rh protein family.”
Rh accessory proteins” is a collective term for other glycoproteins that are associated with the Rh protein family as defined by their absence 5or deficiency from Rhnull RBC's. Together, the association of the Rh protein family and the Rh accessory proteins is called the “Rh complex.” While RhAG is apparently critical for the correct assembly of the Rh proteins in the RBC membrane, RhAG by itself can form stable complexes, albeit in reduced quantity, in the absence of Rh proteins.
Rh antigens appear early during erythropoietic differentiation. In the fetus, Rh antigens are expressed on the RBC's from the 6-week conceptus.19,20
Biochemical studies, protein purification, and amino acid sequencing of Rh and RhAG are have been reviewed in detail elsewhere.2123
 
D Antigen
The D antigen is a collection of conformation-dependent epitopes along the entire RhD protein. D is by far the most immunogenic of Rh antigen, being at least 20 times more immunogenic than C, the next most potent Rh antigen. While in most D-negative Caucasians there is a deletion of RHD, in other populations (notably Japanese and African blacks) the D-negative phenotype is associated with a grossly normal RHD, and the reason for the lack of expression of the D antigen is not known (except in African).
People whose RBCs have an altered form of RhD protein (partial D) may make alloanti-D. Such RBCs, depending on which D epitopes are altered, are agglutinated by a proportion of anti-D reagents.
Analysis of genes encoding the weak D phenotype (previously known as Du) showed a normal RHD sequence but a severely reduced expression of RHD messenger RNA (mRNA), suggesting a defect at the level of transcription or pre-mRNA processing.24 More recently, RHD transcripts from people whose RBC's express a weak form of the D antigen were found to have missense mutation(s) within the predicted transmembrane or cytoplasmic domains of RhD.25,26 RBCs with some weak D antigens may not be agglutinated by all monoclonal anti-D. People whose RBC's express this type of weak D antigen do not make anti-D.
 
Rh Variants
Rh-variant phenotypes arise through at least 4 mechanisms:
  1. Rearrangements of the tandemly arranged RHCE and/or RHD.
  2. Point mutations in either gene causing amino acid change, with subsequent loss of some epitopes and/or expression of a low-incidence antigen.
  3. Nonsense mutations.
  4. Deletion of nucleotides causing a frameshift and premature stop codon. There is some evidence that there are recombination hot spots due to Alu IV elements in the RH genes.27
    6
Low-incidence antigens associated with partial D antigens Low-incidence antigens associated with some partial D phenotypes are due to novel structures on the RBC surface and are useful markers for the identification of the partial D.28
When using monoclonal anti-D to define D epitopes, it is important to perform the testing at the correct pH, temperature, ionic strength, and antibody concentration, to use RBC's that have been stored appropriately, and to include controls.28
 
Partial and Weak D Phenotypes
The term weak D is recommended for use as against the old term Du. The first described Du and many subsequent examples were shown to be inherited, i.e. a parent who is Du passes on to a child a Du antigen which behaves, when tested with anti-D, as does his own Du (Statson 1946, Race 1948). The “genetic Du” is more frequent in blacks. Du red cells have relatively few D-antigen sites compared with normal D red cells.
People whose RBCs have a weak D phenotype (quantitative D variant) invariably do not make anti-D, whereas people whose RBCs have a partial D phenotype (qualitative D variant with or without weakening of the D antigen) can make alloanti-D. Therefore it is of important to differentiate the two. This presents a different problem depending on whether the person is a donor or a patient. For donors, detection of weak and partial D antigens would eliminate the possibility of immunization should such blood be transfused to a true D-negative patient. However, historical data show that weakly expressed D antigens are most unlikely to be immunogenic. For transfusion recipients and pregnant women, it is common practice to use a procedure that will classify RBCs with a weak D antigen or some partial D antigens as D-negative. Thus, blood donated from such a person should be labeled as D-positive (Rh-positive), but the same person should be listed as D-negative (Rh-negative) when they are recipients in need of transfusion. The transfusion recipient will receive D-negative RBC products, and the pregnant woman will receive prophylactic Rh immunoglobulin, thereby preventing alloimmunization. Although a pregnant woman with the DVI partial phenotype may make alloanti-D, this has rarely caused a clinical problem to a D-positive fetus.29 In practice, it is difficult to distinguish RBCs with the DVI phenotype from other weak D; however, this now can be accomplished by immunoblotting with the unique anti-D, LOR-15C9.30
 
Less Common Alleles
Less frequently encountered alleles or Rh variants have been described over the years Cw, Cx, cv, Cu, G, V, Goa, Dw, Eu, Ew, hrs, hrB ET, ei, Rhnull, etc.7
Neil D Avent has very comprehensively dealt with an overview of Rh system.31
 
Rhnull Disease
RBCs from people who have the Rhnull phenotype (synonyms: Rhnull syndrome, Rhnull disease) lack Rh proteins and, thus, Rh antigens. First described by Vos et al in 1961 in an Australian aboriginal woman32 and given the name Rhnull by Ceppelini. This phenotype is rare3336 (approximately 1 in 6 × 106 individuals)37 and most often results from a consanguineous mating. The syndrome is associated with stomatocytosis, spherocytosis, increased osmotic fragility, altered phospholipid asymmetry, altered cell volume, defective cation fluxes, and elevated Na+/K+ ATPase activity.21,38 Rhnull RBCs may have a shortened in vivo survival, and the person may have a mild compensated hemolytic anemia.
There are 2 types of Rhnull, amorph and regulator, that historically were classified based on their pattern of inheritance. It is now known that the amorph type is the result of a molecular change in RHCE in tandem with a deleted RHD, whereas the regulator type is associated with a molecular defect in RHAG. People whose RBCs have a rare deleted Rh phenotype (Rhnull, D_ _ _) readily make alloantibodies. People with the Rhnull phenotype of amorph or regulator type can make anti-Rh29 (an antibody to “total” Rh), anti-Rh17 (an antibody to the RhCc/Ee protein), anti-D, anti-C, or a mixture of specificities. Transfusion of a patient with anti-Rh29 is a problem because only Rhnull RBCs will be compatible: People with the Rhnull phenotype are not only rare, but they have a compensated hemolytic anemia and are therefore unlikely to meet predonation criteria.
 
LW Antigens
The originally described anti-Rh in 1940 was proved to have a different specificity than Anti-D. Dr Levine had suggested the name anti-LW to this specificity in honour of Landsteiner and Wiener. LW antigens are more abundant on D-positive RBCs than on D-negative RBCs from adults, which led to the initial interpretation that anti-D and anti-LW were the same.10 However, LW being located on chromosome 19 is genetically independent of the Rh locus located on chromosome 1. It is possible that the LW glycoprotein interacts preferentially with RhD as compared with RhCcEe; however, the nature of such an interaction awaits definition. Interestingly, LW antigens are expressed equally well on D-positive and D-negative RBCs from fetuses and newborns and more strongly than on RBCs from adults.39,40 While the LW glycoprotein is absent from RBCs of LW(a_b_) and Rhnull individuals, expression of Rh antigens is normal on LW(a_b_) RBCs.8
 
Rh Genotype, Phenotype and Inheritance
The number of phenotypes that can be distinguished depends of course on the number of different antisera with which red cells are tested, e.g. if anti-D alone is used only two phenotypes, D-positive and D-negative, can be distinguished. In the Indian population 95 percent are RhD positive and 5 percent are RhD negative as compared to Caucasian population where 15 percent are RhD negative.
Testing with anti-D, anti-C, anti-E, anti-c and anti-e divides a population into 18 phenotypes. In a few cases, e.g. rr (ccddee) and r'r'(CCddee), the phenotype discloses the only possible genotype but some of the other phenotypes include a number of genotypes, e.g. the phenotype R1 R2 (CcDEe). The use of anti-e is often confined to tests on red cells which are C negative, E positive, since it is only in these circumstances that the additional information obtained justifies the use of this less common and expensive antiserum.
In relevance to HDN, when a woman has anti-D in her serum it is desirable to know whether the parent is homozygous or heterozygous for the gene determining D, i.e. whether he is DD or Dd. If he is DD he can father only D-positive infants but if he is Dd there will be 50 percent chance that the child will be D negative and so will be unaffected by the anti-D in the woman's plasma.20 Therefore the significance in prognosis in families where HDN occurs.
It will be appreciated from the foregoing that in only a few cases will tests, even with all the available antisera, disclose the actual genotype of an individual. At best a probable genotype may be deduced from the frequency with which each occurs within a particular phenotype. For example, within the phenotype whose pattern of reaction is++++ the genotype R1 R2 (CDelcDE) is 88.4 percent of the phenotype. This means that the probable genotype, therefore, of an individual in this phenotype is R1R2 (CDelcDE).
A more accurate assessment of genotype can sometimes be made with the aid of family studies.
An example of a less complicated phenotype mating is given below:
Genotypes of
Phenotypes of
Phenotype mating
children
children
r'r × rr
r'r and rr
rr and rr
In this case of course it is possible to determine the actual genotype with the four antisera anti-C, anti-D, anti-E and anti-c and family studies will merely confirm the findings.9
 
D-negative Genotypes
The subdivisions of the D-negative individuals are:
  1. cde / cde (rr)
  2. Cde / cde (r'r)
  3. Cde / Cde (r'r')
  4. Cde / cdE (r'r”)
  5. Cde / CdE (r'ry)
  6. cdE / cde (r”r)
  7. cdE / cdE (r“r”)
  8. cdE / CdE (r”ry)
  9. CdE / cde (ryr)
  10. CdE / CdE (ryry).
Most of the foregoing genotypes are very rare and thus seldom encountered. The most important is, of course, No 1. cde/cde, after which 2. Cde/cde and 6. cdE/cde are the most frequent. These individuals are all capable of making anti-D if stimulated by the D antigen and should, if in need of a blood transfusion, receive blood which is either Rh negative (cde/cde) or of their own genotype. Since the latter alternative is almost always impracticable all of these must be regarded as Rh negative recipients.
It can be seen that all but the true Rh negatives (cde/cde) have either C or E or both of these antigens and if they are used as Rh negative donors for transfusion they may stimulate the production of anti-C or anti-E in the recipient. This means that every donor who is negative with anti-D must be tested further with anti-C and anti-E. Mixtures which contain anti-D as well are also used.
 
Principles of Rh Typing
At the practical level of the transfusion laboratory, in conjunction with ABO grouping, D-typing is usually all that is necessary for patients prior to transfusion. D antigen is most immunogenic being at least 20 times more immunogenic than c, the next most common Rh antigen. Once the basic tests are done in any laboratory, any abnormal sample can be referred to a specialized lab for further work-up.
The tube technique with an incubation time of at least one hour should be the yardstick by which all other techniques are judged. The antiglobulin, LISS, microplate41 and enzyme methods are used for the detection and identification of Rh antibodies. Enzyme techniques particularly the papain two-stage method has definitive value since many examples of Rh antibodies particularly other than anti-D work best by the papain technique.
 
Interpretation of Results of D-typing
It is recommended that D-typing be performed with two anti-D sera. A negative result with both sera will mean that the blood sample under test is probably D-negative; it should not, however, be regarded as completely Rh negative without further testing for the other Rh antigens. This further testing can be omitted in an emergency since a patient who is negative 10with two anti-D sera must always receive Rh negative blood. A positive result (V or + +) with both anti-D sera will mean that the sample is almost certainly Rh positive and for all practical purposes can be so considered. Weak –D (High grade Du) red cells may also be positive with both anti-D sera, but such cells are treated as Rh positive for all practical purposes. Samples which give doubtful reactions (+, (+) or w) with one or both antisera should be re-tested, if possible, with a larger range of anti-D sera.
A negative result with one serum and a positive with the other is also an indication for testing against a number of anti-D sera (see weak/partial D). No specific antisera have not been found for them. The testing must be carried through the anti globulin phase to demonstrate the presence of D antigen. In the past a high grade Du red cell was described as one that is agglutinated by the majority of anti-D sera by saline or albumin technique a low grade Du red cell is described as one which is agglutinated by saline or albumin technique by only one or two of a range of sera with which it is tested, although it is sensitized by most of them, as can be proved by testing with antiglobulin and it will normally react by papain two-stage technique.
 
Controls
Whatever technique is used controls are necessary. For any anti-D typing three controls should be used:
  1. Known D positive cells with the standard anti-D serum
  2. Known D negative cells with the standard anti-D serum
  3. The unknown cells with a bland serum (group AB) with the addition of bovine albumin if the technique employed involves its use.
A satisfactory positive control is one which corresponds to the weakest positive expected to be found in the tests. Accordingly, cells that are heterozygous for each antigen tested are used.
R1 R2 (CcDEe) cells are obviously the convenient choice for a positive control which satisfies the foregoing criterion for all antisera except anti-D for which R1r (CcDee) cells are the best control. The negative control for each antiserurn has to be selected with the possible contaminants of that serum in mind. Very strong anti-C, anti-E and anti-c sera are not common and so weaker examples of them may have to be used for test sera than if the selection were wider.
If the negative control cells under test with AB serum (point 3 above) is positive, then no positive results obtained with the standard anti-sera can be relied upon and the phenomena is to be fully investigated.
For detailed methodology of tests please refer to standard textbooks of blood banking.11
REFERENCES
  1. Landsteiner K Uber: Agglutination seruscheinungen normalen menschlichen Blutes [Agglutination phenomena in normal human blood]. Wien Klin Wochenscher 14: 1132, 1901. [An English translation, by A.L. Kappus, appears in transfusion 1: 5–8, 1961].
  1. Levine P, Stetson RE: An unusual case of intragroup agglutination. Journal of the American Medical Association (JAMA) 113: 126–27, 1939.
  1. Landsteiner K, Wiener AS: An agglutinable factor in human blood recognised by immune sera for rhesus blood. Proc Soc Exp Biol Med (NY) 43: 223–24, 1940.
  1. Levine P, Celano MJ, Wallace J, et al: A human ‘D-like’ antibody. Nature 198: 596–97, 1963.
  1. Levine P, Burnham L, Katzin EM, et al: The role of iso-immunisation in the pathogenesis of erythroblastosis fetalis. Am J Obstet Gynecol 42: 925, 1941.
  1. Levine P, Katzin EM, Burnham L: Iso-immunisation in pregnancy, its possible bearing on the etiology of erythroblastosis fetalis. Journal of the American Medical Association (JAMA) 116: 825, 1941.
  1. Levine P, Vogel P, Katzin EM, et al: Pathogenesis of erythroblastosis fetalis: Statistical evidence. Science 94: 371, 1941.
  1. Race RR: The Rh genotypes and Fisher's Theory. Blood 3(suppl 2): 27–42, 1948.
  1. Colin Y, Cherif-Zahar B, Le van Kim, et al: Genetic basis of the Rh-D positive and Rh-D negative blood group polymorphism as determined by Southern blot analysis. Blood 78: 1–6, 1991.
  1. Wiener AS: Genetic theory of the Rh blood types. Proc Soc Exp Biol (NY) 54: 316–19, 1943.
  1. Rosenfield RE, Allen FH Jr, Swisher SN, et al: A review of Rh serology and presentation of a new terminology. Transfusion 2: 287–312, 1962.
  1. Rosenfield RE, Allen FH Jr, Swisher SN, et al: Rh nomenclature. Transfusion 19: 487, 1979.
  1. Issitt PD, Anstee DJ: Applied Blood Group Serology. 4th edition Durham, NC: Montogomery Scientific, 1998.
  1. Reid ME, Lomas-Francis C: The blood group antigen factsbook. New York: Academic Press,  1997.
  1. Allen FH Jr, Anstee ill, Bird GWG, et al: ISBT Working Party on Terminology for Red Cell Surface Antigens. Vox Sang 42: 164–65, 1982.
  1. Daniels GL, Anstee DJ, Cartron JP, et al: Blood group terminology 1995: ISBT working party on terminology for red cell surface antigens. Vox Sang 69: 265–79, 1995.
  1. Daniels GL, Anstee DJ, Cartron JP, et al: Terminology for red cell surface antigens. ISBT Working Party Oslo Report. International Society of Blood Transfusion. Vox Sang 77(1): 52–57, 1999.
  1. Garraty G, Dzik W, Issitt PD, et al: Terminology for blood group antigens and genes-historical origins and guidelines for the new millennium. Transfusion 40: 477–89, 2000.
  1. Chérif-Zahar B, Bloy C, Le Van Kim C, et al: Molecular cloning and protein structure of a human blood group Rh polypeptide. Proc Natl Acad Sci USA 87: 6243–47, 1990.
  1. Mollison PL, Engelfriet CP, Contreras M: Blood Transfusion in Clinical Medicine. Oxford, England: Blackwell Science;  1997.
  1. Agre P, Cartron JP: Molecular biology of the Rh antigens. Blood 78: 551–63, 1991.
  1. Huang CH: Molecular insights into the Rh protein family and associated antigens. Curr Opin Hematol 4: 94–103, 1997.
  1. Mouro I, Colin Y, Chérif-Zahar B, et al: Molecular genetic basis of the human Rhesus blood group system. Nature Genet 5: 62–65, 1993.
  1. Rouillac C, Gane P, Cartron J, et al: Molecular basis of the altered antigenic expression of RhD in weak D (Du) and RhC/e in RN phenotypes. Blood 87: 4853–61, 1996.
  1. Legler TJ, Maas JH, Blaschke V, et al: RHD genotyping in weak D phenotypes by multiple polymerase chain reactions. Transfusion 38: 434–40, 1998.
  1. Wagner FF, Gassner C, Müller TH, et al: Molecular basis of weak D phenotypes. Blood 93: 385–93, 1999.
  1. Kemp TJ, Poulter M, Carritt B: A recombination hot spot in the Rh genes revealed by analysis of unrelated donors with the rare D phenotype. Am J Hum Genet 59: 1066–73, 1996.

  1. 12 Tippett P, Lomas-Francis C, Wallace M: The Rh antigen D: Partial D antigens and associated low incidence antigens. Vox Sang 70: 123–31, 1996.
  1. Lacey PA, Caskey CR, Werner DJ, et al: Fatal hemolytic disease of a newborn due to anti-D in an Rh-positive Du variant mother. Transfusion 23: 91–94, 1983.
  1. Reid ME, Halverson GR, Roubinet F, et al: Use of LOR-15C9 monoclonal anti-D to differentiate erythrocytes with the partial DVI antigen from those with other partial D antigens or weak D antigens. Immunohematology 14: 89, 1998.
  1. Avent ND, Reid ME: The Rh blood group system: A review. Blood 95(2): 375–87, 2000.
  1. Vos GH, Vos, Dell, Kirk RL, et al: A sample of blood with no detectable Rh antigens. Lancet i: 14, 1961.
  1. Ishimori T, Hakesura H: A Japanese with no detectable Rh blood group antigens due to silent Rh alleles or chromosomes. Tansfusion 7: 84, 1967.
  1. Levine P, Celano MJ, Fallowski F et al: A second example of - - - / - - -, or Rhnull blood. Transfusion 5: 492, 1965.
  1. Senhauser DA, Mitchello MW, Gault GB, et al: Another example of phenotype Rhnull. Transfusion 10: 89, 1970.
  1. Schmidt PJ, Vos GH: Multiple phenotypic abnormalities associated with Rh null (- - - / - - -). Vox Sang 13: 18–20, 1967.
  1. Seidl S, Spielmann W, Martin H: Two siblings with Rhnull disease. Vox Sang 23: 182–89, 1972.
  1. Ballas SK, Clark MR, Mohandas N, et al: Red cell membrane and cation deficiency in Rh null syndrome. Blood 63: 1046–55, 1989.
  1. Giles CM: The LW blood group: A review. Immunol Commun 9: 225–42, 1980.
  1. Mallinson G, Martin PG, Anstee DJ, et al: Identification and partial characterization of the human erythrocyte membrane component(s) that express the antigens of the LW blood-group system. Biochem J 234: 649–52, 1986.
  1. Llopis F, Carbonell-Uberos F, Montero MC, et al: A new method for phenotyping red blood cells using microplates. Vox Sang 77(3): 143–48, 1999.