Rare RHCE phenotypes in black individuals of Afro-Caribbean origin:: identification and transfusion safety

The molecular backgrounds of variants encountered in Afro-Caribbean black individuals and associated with the production of clinically significant antibodies against high-incidence antigens (antiRH18, anti-RH34) and against Rhe epitopes were determined. We showed that RH:-18 phenotypes are produced by 3 distinct RHCE alleles: ceEK carrying 486>C (axon 1), 712A>G, 787A>G, 800T>A (exon 5); ceB1 carrying 486>C (exon 1), 712A>G (exon 5), 818C>T (axon 6), 1132C>G (axon 8); and the already known ceAR allele carrying 486>C (axon 1), 712A>G, 733C>G, 787A>G, 800T>A (exon 5), and 916A>G (axon 6). The RH: -34 phenotype is produced by the (C)ce(S) haplotype described previously and composed of a hybrid D-CE(3-8)-D gene with 4 extra mutations next to a ce(s) allele (733C>G; axon 5) with an extra mutation in exon 7 (1006G>T). Partial Rhe with risk of immunization against lacking epitopes can be produced by the new ces allele carrying an extra mutation in axon 3 (340C>T) and by the ceMO allele described previously. A population of sickle cell disease patients was screened to estimate the incidence of these rare alleles, with the conclusion that a procedure is required to detect the associated phenotypes in black donors to ensure transfusion safety for patients. We also described a new variant [ce(S)(748)] and variants carrying different altered alleles in nonimmunized patients and for whom the risk of immunization is discussed. (Blood.2002;100:4223-4231) (C) 2002 by The American Society of Hematology.