Prevalence of DEL phenotype in D– blood donors in India

Unlike weak D and partial D, DEL represents a weakened form of D that cannot be detected by conventional serology and requires use of an adsorption-elution method for its detection; therefore, DEL+ samples might be mistyped as D–. The study was undertaken to determine the prevalence of the DEL phenotype among D– blood donors from northern India. A total of 1003 D– blood donors were tested for weak D and DEL by the indirect antiglobulin test and an adsorption-elution method, respectively. Of the total 21,135 blood donors typed for D, 20,132 (95.3%) were D+ and 1003 (4.7%) gave a negative reaction for D. Of the total 1003 D– samples, 8 (0.8%) were weak D and only 2 (0.2%) were DEL+ by adsorption-elution testing. For samples that typed as D–, the majority of individuals (91.1%) were cde/cde (rr) followed by dCe/dce (r´r) in 4.8 percent, and dCe/dCe (r´r´) in 2.2 percent. Both DEL+ samples were also C+. We conclude that the prevalence of the DEL phenotype as detected by serology in D– north Indian blood donors is 0.2 percent, although it is as high as 2.8 percent in D–C+ individuals. There is an association of DEL with C, which can be used as a cost-effective marker for screening large numbers of D– blood donors for DEL.