Variant RHD alleles and Rh immunization in patients with sickle cell disease.

Summary: RH diversity among patients and donors contributes to Rh immunization despite serologic Rh‐matched red cell transfusions. Anti‐D can occur in D+ patients with RHD variants that encode partial D antigens. Anti‐D has also been reported in patients with conventional RHD transfused primarily with units from Black donors who frequently have variant RHD. We report 48 anti‐D in 690 D+ transfused individuals with sickle cell disease, categorized here as expressing conventional D, partial D or D antigen encoded by RHD*DAU0. Anti‐D formed in a greater proportion of individuals with partial D, occurred after fewer D+ unit exposures, and remained detectable for longer than for those in the other categories. Among all anti‐D, 13 had clinical or laboratory evidence of poor transfused red cell survival. Most individuals with anti‐D were chronically transfused, including 32 with conventional RHD who required an average of 62 D− units/year following anti‐D. Our findings suggest that patients with partial D may benefit from prophylactic D− or RH genotype‐matched transfusions to prevent anti‐D. Future studies should investigate whether RH genotype‐matched transfusions can improve use of valuable donations from Black donors, reduce D immunization and minimize transfusion of D− units to D+ individuals with conventional RHD or DAU0 alleles. [ABSTRACT FROM AUTHOR]