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.