Determination of Rhd Zygosity in India: To Prevent Hemolytic Disease of Newborn

Abstract

Objective:To access the prevalence of RhD heterozygosity rates in phenotypically RhD positive Indians using two different genotyping techniques. Material and Methods: Husbands of women with RhD negative blood group, attending outpatient department were recruited for study. RhD zygosity was done in blood samples of Rh positive husbands by two different methods. DNA was isolated by using conventional phenol-chloroform method. For RhD zygosity determination two methods polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polymerase chain reaction-sequence-specific primer (PCR-SSP) techniques were used for each sample. Results: Of the 105 women with RhD negative blood group, husband’s blood group was found to be Rh D negative in 5 (4.8%). Of the 100 blood samples that were found RhD positive, zygosity analysis showed that 26 were D heterozygous by both methods. Hence RhD heterozygosity rate in India is 26%. Conclusion:Women with husbands having homozygous RhD positive (DD) are likely to have all fetus RhD positive (Dd) and hence not require molecular technique like fetal blood group determination from maternal plasma. While 26% of women whose husband are RhD positive by serology and heterozygous for RhD deletion by molecular methods require fetal blood group determination from maternal plasma. Hence, knowing the RhD zygosity of the husband, fetal blood group determination from maternal plasma is required to be done in one fourth of women having RhD isoimmunisation.