OBJECTIVE: To explore the molecular mechanism of a case with RhD-- phenotype. METHODS: A proband with RhD-- phenotype who attended the clinic of the First Affiliated Hospital of Zhengzhou University on January 29, 2024 was selected as the study subject. Peripheral blood samples were collected from the proband (8 mL) and her close relatives (father, mother and brother; 3 mL each) for Rh phenotyping and irregular antibodies testing with gel card and test tube methods. Direct agglutination reaction and absorption-elution test were used to detect the c antigen on the red blood cells of the proband. PCR-sequence specific primers (PCR-SSP) typing and gene sequencing were used to determine the RHCE gene of the proband and her relatives. The origin of the proband's variant was traced by pedigree analysis. Three-dimensional structural models of the wild-type RhCE*cE protein and the RhD-- phenotype protein were constructed to predict the alterations of the RhD-- phenotype protein caused by the variant. The procedures of this study were approved by the Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (Ethics No.: 2023-KY-0870-003). RESULTS: The red blood cells of the proband did not agglutinate with anti-C, anti-c, anti-E, and anti-e. The result of the serum irregular antibody test was negative. The results of direct agglutination reaction and absorption-elution test of the proband were both negative. Her Rh blood group was identified as RhD--. The results of the Rh blood grouping of her close relatives were normal. PCR-SSP detection showed that the RHCE genotypes of the proband and her close relatives were cE/cE and Ce/cE, respectively. Gene sequencing analysis showed that the RHCE genotypes of the proband and her close relatives were RHCE*cE (c.365C>A)/RHCE*cE (c.365C>A) and RHCE*Ce/RHCE*cE (c.365C>A), respectively. Pedigree analysis revealed that the variants in the proband were inherited from her father and mother, respectively. Homology modeling of RhCE*cE protein showed that the RhD-- type peptide chain with a significantly shortened C-terminal was encoded by only 121 amino acid resides, which was 296 amino acid resides shorter compared to the wild-type RhCE*cE peptide chain encoded by 417 amino acid residues. CONCLUSION Above results revealed the molecular biological mechanism of a RhD-- phenotype. The c.365C>A variant in the RHCE gene has rendered the RHCE*cE alleles invalid, which ultimately led to the RhD-- phenotype.
Humans ; Rh-Hr Blood-Group System/chemistry* ; Female ; Phenotype ; Male ; Alleles ; Pedigree ; Base Sequence ; Molecular Sequence Data ; Adult

The aim of this study was to clone human RHD gene and to investigate its expression in transduced K562 cells. Total RNA was extracted from reticulocyte of cord blood. RHD and RHCE genes were amplified using RT-PCR method. The amplified products were cloned into pGEM-T plasmid by TA ligation and several clones were screened by direct sequencing method in order to obtain the RHD gene. RHD gene was subcloned into pcDNA3.1(-) expression vector, then the recombined plasmids were transduced into K562 cells with superfect transfection reagent kit. Finally transcription and expression of RHD gene in K562 cells were detected. The result showed that RHD gene has been cloned sucessfully, the inserted sequence and direction of RHD cDNA in its recombined pcDNA3.1(-) vector were identified using enzyme cutting and sequencing method. After transduced with recombined pcDNA3.1(-) vector, K562 cells could transcribe RHD mRNA in its cytoplasm and express RhD antigen on its membrane surface. In conclusion, RhD antigen can expressed in K562 cells with RHD cDNA transduction, and the expression system in vitro may be helpful to further investigate the molecular basis of RhD variants.
Base Sequence ; Cell Membrane ; metabolism ; Cloning, Molecular ; DNA, Complementary ; chemistry ; genetics ; Gene Expression ; Genetic Vectors ; genetics ; Humans ; K562 Cells ; Molecular Sequence Data ; RNA, Messenger ; biosynthesis ; genetics ; Rh-Hr Blood-Group System ; biosynthesis ; genetics ; Sequence Analysis, DNA ; Transfection