RHD positive among C/E+ and D− blood donors in Denmark

BACKGROUND: Many different partial and weak D types have been reported, and most of these are easily detected by serology. However, 17 Del types have also been described, with a very low expression of the D antigen, only detectable by absorption-elution techniques, and these may elicit the development of an anti-D. A genomic test of C/E+ and D- blood donors was initiated, to be able to categorize them correctly as D+ or -. STUDY DESIGN AND METHODS: We analyzed all C/E+ and D- donors within our donor population of 22,000 donors with an initial test for RHD Exon 10. In case of a positive reaction, the genotype was further analyzed by sequence-specific polymerase chain reaction or nucleotide sequencing of the RHD gene. CONCLUSIONS: Of 233 donors analyzed, seven were found positive for RHD Exon 10, and four of these were Del, corresponding to 1.7%. We report here a new mutation in the RHD gene. A correct assignment of all blood donors as D+ or D- is not possible using serotyping alone; genotyping offers the only exact categorization of all cases.