Objective: To explore the molecular basis of two individuals with weak D variant of the Rh blood type.
Methods: Routine serological testing was carried out to detect the D, C, c, E and e antigens of the Rh blood group. The D antigen was further detected with an indirect antiglobulin test. The presence of Rhesus box was detected by PCR to determine the homozygosity of the RHD gene.
Results: Both samples were determined as weak D phenotype by the indirect antiglobulin test. DNA sequencing revealed that case 1 harbored a heterozygous 208C>T variant in exon 2 and a heterozygous 1227G>A variant in exon 9; while case 2 harbored homozygous 779A>G variants of exon 5 of the RHD gene. Case 1 was determined as RHD+/RHD+, while case 2 was determined as RHD+/RHD-. The two samples were respectively named as weak D type 122 and weak D type 149 based on the rules of Rhesus Base Nomenclature.
Conclusion: D negative blood donors should subject to indirect antiglobulin testing and molecular analysis for safer transfusion.