Molecular background of RH in Bastiaan, the RH:-31,-34 index case, and two novel RHD alleles.

Anti-hr(B) (-RH31) and anti-Hr(B) (-RH34) were found nearly 40 years ago in the serum of a South African woman. The anti-hr(B) was revealed after adsorption with DcE/DcE red blod cells (RCBs). Numerous anti-hr(B), in the absence of anti-Hr(B), have since been identified. We obtained a sample of blood from this index case (Bastiaan) and report the molecular basis of her D+C-E-c+e+/-, V-VS+Hr+hr(S)+hr(B)-Hr(B)- phenotype as well as results of testing her RBCs using currently available regents. We tested a cohort of African Americans to estimate the frequency of the RHCE*ce 48C,733G,1006T allele, and in addition found two novel RHD alleles. Hemagglutination tests and DNA analyses were performed by standard methods. Analyses revealed homozygosity for RHCE*ce 48C,733G,1006T in Bastiaan. RBCs from Bastiaan were strongly agglutinated by three commercial anti-e reagents. Testing RBCs from people homozygous for RHCE*ce 48C,733G,1006T showed that anti-e MS16, MS17, and MS63 were weakly reactive or non reactive, MS21 was strongly reactive, and HIRO38, HIRO41, and HIRO43 were non reactive. Results show that Bastiaan has RHD*DIIIa150C and RHD*DIIIa-CE(4-7)-D. Tests on 605 samples from random African Americans revealed a frequency of 0.036 for RHCE*ce 48C,733G,1006T and revealed two novel alleles: RHD*186T and RHD*DIIIa150C. The Bastiaan phenotype is encoded by RHD*DIIIa150C-RHCE*ce 48C,733G,1006T and RHD*DIIIa-CE(4-7)-D-RHCE*ce 48C,733G,1006T ; thus, this genotype is the gold standard for the hr(B)-Hr(B)-phenotype. The r'(s) complex encodes VS, which explains why most hr(B)-RCBs are VS+.

Molecular basis of the rare gene complex, DIVa(C)-, which encodes four low-prevalence antigens in the Rh blood group system.

BACKGROUND: Over 40 years ago, an unusual Rh phenotype denoted DIVa(C)- was identified in a case of fatal haemolytic disease of the newborn in the third child of Madame Nou. Her RBCs expressed a partial D, weak C and four low-prevalence Rh antigens: Go(a) (RH30), Rh33 (RH33), Riv (RH45) and FPTT (RH50). The purpose of this study was to determine the molecular basis associated with this rare DIVa(C)- complex. MATERIAL AND METHODS: Blood samples were from three donors previously identified as carrying the DIVa(C)- haplotype. Molecular analyses were performed by standard methods. RESULTS: The three donors were heterozygous for RHD and RHD*DIVa.2, and all carried a compound hybrid allele at the RHCE locus. This hybrid RHCE allele contained exons 2 and 3 from RHD*DIVa.2 and exon 5 from RHD [RHCE*CE-DIVa.2(2-3)-CE-D(5)-CE] and is in cis to RHD*DIVa.2. The RHCE allele on the in trans chromosome differs between the donors and is RHCE*cE in donor 1, RHCE*ce (254C, 733G) in donor 2 and RHCE*ce in donor 3. CONCLUSIONS: The RHD*DIVa.2 encodes the Go(a) antigen, whereas the compound hybrid allele most likely encodes Rh33, Riv and FPTT. The weakly expressed C antigen on RBCs with the DIVa(C)- phenotype could be encoded by exons 2 and 3 from RHD*DIVa.2 in the compound hybrid. This is the first report of RHD*DIVa.2 being involved in a hybrid gene at the RHCE locus. As only one example of anti-Riv has been described, our molecular analysis and findings provide a tool by which to predict Riv expression.