[Molecular study of a case with variant of RHCE*ce allele in haplotype dce resulting in weakened e antigen]

To explore the Rh genotype for a female with RhD(-) blood type and its molecular basis.

A 26-year-old female who had attended the outpatient clinic of the First Affiliated Hospital of Zhengzhou University in August 2019 was selected as the study subject. Peripheral blood samples were collected from the proband and her parents for Rh phenotyping with gel card method. PCR-sequence-based typing (PCR-SBT) and DNA sequencing were used to determine the RHD zygosity and Rh genotype of the proband and her parents. Homology modeling of Rh proteins was performed with bioinformatic software, and protein structural alterations caused by the variant was simulated by molecular dynamics.

Serological tests showed that the proband and her father both had weakened e antigen of the Rh phenotype. PCR-SBT and DNA sequencing showed that the genotypes of the proband and her parents were dce/dCE, dce/DcE and dCE/DcE, respectively. And the genotypes of the RHD and RHCE of the proband were RHD*01N.01/RHD*01N.16, RHCE*01.01/RHCE*04, respectively. Protein simulation and molecular dynamics analysis revealed that the ce_16C variant resulted from RHCE*ce (c.48G>C) may alter the structure of intracellular and extracellular loops, mainly affecting the mobility of extracellular loops 2, 6 and intracellular loops 3, 4.

Variant of the RHCE*ce allele c.48G>C probably underlay the weakened e antigen in this proband.