Identification of RHCE and KEL alleles in large cohorts of Afro-Caribbean and Comorian donors by multiplex SNaPshot and fragment assays: a transfusion support for sickle cell disease patients

To lower the alloimmunization risk following transfusion in blacks, we developed two genotyping assays for large-scale screening of Comorian and Afro-Caribbean donors. One was a multiplex SNaPshot assay designed to identify ce(s)(340), ceMO/AR/EK/BI/SM, ce(s), ce(s) (1006) and KEL*6/*7 alleles. The other was a multiplex fragment assay designed to detect RHD, RHD psi and RHCE*C and 455A>C transversion consistent with (C)ce(s) Type 1 and DIII Type5 ce(s). Variant RHCE*ce alleles or RH haplotypes were detected in 58.69% of Comorians and 41.23% of Afro-Caribbeans. The ce(s) allele, (C) ce(s) Type 1, and DIII Type 5 ce(s) haplotypes were identified respectively in 39.13%, 14.67% and 4.88% of Comorians and 32.23%, 5.28% and 1.76% of Afro-Caribbeans. Genotypes consistent with partial D, C, c and/or e antigen expression were observed in 26.08% of Comorians and 14.69% of Afro-Caribbeans. No homozygous genotype corresponding to the RH:-18, -34, and -46 phenotypes were found. However, over 50% of genotypes produced low-prevalence antigens at risk for negative recipients, i.e., V, VS, JAL, and/or KEL6. One new variant RHCE*ce(s) (712) allele was identified. This is the first determination of variant RHCE and KEL allele frequencies. Results indicate the most suitable targets for molecular assay screening to optimize use of compatible blood units and lower immunization risk.