Molecular genetic analysis of two individuals with weak D variant of the Rh blood type

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.