Molecular basis of D variants in Chinese persons

BACKGROUND: Most studies of the molecular basis of D variants have been conducted in Caucasian and African populations. There are limited data on the molecular basis for D variants in Chinese populations. STUDY DESIGN AND METHODS: With a blended monoclonal anti-D and a sequential slide and tube typing protocol, red blood cells from greater than 99 percent of Han Chinese were tested for the D antigen. Samples that agglutinated weakly by tube method or that reacted only by indirect antiglobulin test (IAT) were classified as D variants. The D variant was tested by an RHD polymerase chain reaction with sequence specific primers and by gene sequencing to distinguish and characterize weak D and partial D alleles. RESULTS: Of 305,572 samples from individual donations (305,475 [99.97%] were ethnic Han and 97 [0.032%] were ethnic minorities), 304,134 (99.53%) typed as D+. Five (0.0016%) typed as D variants (weak agglutination by tube). By IAT an additional 32 (0.0105%) typed as D variants and 1401 (0.46%) typed as D-. Weak D type 15 and RHD(K409K) alleles represented 72.7 percent of all weak D phenotypes. All partial D phenotypes were DVI Type 3 or DV. Three new weak D alleles carrying 594A > T and 602C > G (weak D Type 51), 92T > C (weak D type 52), and 740T > G (weak D type 53) mutations, respectively, were identified. CONCLUSION: There are significant differences in the frequencies and molecular characteristics of D variants among indigenous Chinese populations, compared to Caucasian and African populations, which must be considered when developing clinical practices related to D variant blood donors, transfusion recipients, or obstetrical patients.