RHCE*ceTI encodes partial c and partial e and is often in cis to RHD*DIVa

Abstract

BACKGROUND: In the Rh blood group system, variant RhD and RhCE express several partial antigens. We investigated RH in samples with partial DIVa that demonstrated weak and variable reactivity with anti‐C. STUDY DESIGN AND METHODS: Standard hemagglutination techniques, polymerase chain reaction–based assays, and RH sequencing were used. RESULTS: DNA analysis showed that six red blood cell (RBC) samples with weak and inconsistent reactivity with anti‐C lacked RHCE*C, but all had RHD*DIVa, which encodes partial D and Goa. We then tested RBCs from 19 Go(a+) cryopreserved samples (confirmed to have RHD*DIVa) with four anti‐C and observed weak variable reactions. RHCE genotyping found all but one of the samples with RHD*DIVa also had RHCE nt 48G>C and 1025C>T, named RHCE*ceTI. Lookback of samples referred for workup and found to have either allele revealed 47 of 55 had both RHD*DIVa and RHCE*ceTI, four had RHD*DIVa without RHCE*ceTI, and four had RHCE*ceTI without RHD*DIVa. Alloanti‐c was found in a patient with c+ RBCs and RHCE*ceTI in trans to RHCE*Ce, and alloanti‐e was found in a patient with e+ RBC and RHCE*ceTI in trans to RHCE*cE. RHD*DIVa in trans to RHD erroneously tested as RHD hemizygous. CONCLUSIONS: RHD*DIVa and RHCE*ceTI almost always, but not invariably, travel together. This haplotype is found in people of African ancestry and the RBCs can demonstrate aberrant reactivity with anti‐C. RHCE*ceTI encodes partial c and e antigens. We confirm that RHD zygosity assays are unreliable in samples with RHD*DIVa.

Reliability of labeling red cell units with minor antigen historical results and process considerations

“…Typing of the RBCs with multiple reagents, and RH genotyping on 40, revealed 30 discrepancies associated with partial, weak, or variant Rh antigen expression. This is consistent with the variability in detection of partial Rh antigens by the source reagents on automated PK7300 as we have previously observed, as well as false positive serologic C typing previously reported . For 12 C discrepant samples that were RH genotyped, the following alleles were implicated; RHCE*CeRN (n = 7); RHD*DIVa (n = 2); RHD*D‐CE(4‐7)‐D ( r'S type 2) (n = 1), RHCE*CE (RZ) (n = 1), and one with no changes with weak C expression undergoing further investigation (n = 1).…”

“…Of these, seven were weak false positive C typing by the hospital, six of which were associated with RBCs having a Go(a+) phenotype encoded by RHD*DIVa . As we previously reported, weak reactivity is sometimes observed with Immucor Gamma‐Clone anti‐C with RBCs with this RH genotype, but the RBCs are non‐reactive with Ortho Bioclone, Bio‐Rad Seraclone, and Diagast P3X25513G8 . The same pattern of weak false positive reactivity with Immucor Gamma‐Clone anti‐C, while non‐reactive with all other anti‐C tested, was seen in a sample shown to have RHD*DAU5‐RHCE*ce254G .…”

High prevalence of red blood cell alloimmunization in sickle cell disease despite transfusion from Rh-matched minority donors

“…Rh epitopes and Rh antigen specificities are complex, may be crossreactive with other Rh antigens, and are not always straightforward. RhD-like epitopes, reactive with anti-D, can be expressed on altered Rhce proteins, 31,37 C-like epitopes on variant RhD and Rhce proteins, 32,38 and E-like antigens on RhCe proteins. 39 Thus, future studies will address whether RBCs from African American donors stimulate complex Rh specificities.…”

RHCE*ceAG (254C>G, Ala85Gly) is prevalent in blacks, encodes a partial ce‐phenotype, and is associated with discordant RHD zygosity

“…Two others in agreement (P1, P8) had a novel allele with additional changes and were concordant as RHD hemi‐ and homozygotes, respectively. The sixth (P13) has RHD*DIVa, which is reported to be false‐positive for the 1.5‐kb product in the absence of deletion of RHD . Among the samples with discordant RHD zygosity (Table ), P2 had two RHD alleles by Rh‐cDNA analysis ( RHD*DAU0/D ) but Pst I‐RFLP predicted the sample was hemizygous.…”