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


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 Go(a) . 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.
Laboratory of Immunohematology and Genomics, New York Blood Center, Long Island City, New York 10065, USA. mreid@nybloodcenter.org
Connie M
CM
Westhoff
Sunitha
S
Vege
Christine
C
Halter Hipsky
Kim
K
Hue-Roye
Tamara
T
Copeland
Randall W
RW
Velliquette
Trina
T
Horn
Christine
C
Lomas-Francis
Marion E
ME
Reid
D000328:Adult; D001741:Black or African American / Q000235:genetics; D054458:Amplified Fragment Length Polymorphism Analysis; D005260:Female; D006239:Haplotypes; D006386:Hemagglutination Tests; D006801:Humans; D007518:Isoantibodies; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length; D012204:Rh-Hr Blood-Group System / Q000235:genetics* / Q000276:immunology; D017423:Sequence Analysis, RNA
D007518:Isoantibodies; C066468:RHCE protein, human; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen