Evaluation of molecular typing and serological methods in solving discrepant results of weak and partial D (Rh) in South Egypt

INTRODUCTION: Rh discrepancies produced by partial and weak D phenotypes are a problem during routine testing. Some blood units with weak and partial D expression may be missed by serology. Overcoming the limitations of serology can be achieved by molecular typing. Our objective was to evaluate currently used serologic methods with the molecular analysis in solving discrepant results of weak and partial D (Rh) in South Egypt. PATIENTS AND METHODS: Fifty blood donor and patient samples with undetermined D phenotype were subjected to serology to define their phenotype using identification (ID)-Card “ID-partial RhD typing set” using six monoclonal anti-D panels, followed by molecular typing using polymerase chain reaction sequence-specific primer kit. RESULTS: Molecular typing confirmed most of the serology results; two samples previously resolved as partial D Type 3 and DFR by serological methods were clarified by molecular techniques – one sample as weak Type 4 and the other sample as weak Type 3. Among the weak D alleles found in our study, Type 4 was the most common, with a frequency of 20%, followed by Type 3 (14%), Type 1 (8%), Type 2 (6%), and finally, Type 5 with a frequency of 3%. The most common types of partial D were partial D Type D5 (14%) and Type D3 (10%). CONCLUSION: Our study identified D variants (weak D and partial D categories) of the antigen D and determined the frequency and composition of partial D and weak D alleles in our population. Molecular typing also confirmed most of the results obtained from serological methods.