[Serological characteristics and bioinformatics analysis of 4 blood donors with RHCE*cE(281C,282T) variant allele].

Objective: To explore the serological characteristics and bioinformatics analysis results of 4 blood donors with RHCE*cE(281C, 282T) variant allele.

Methods: A total of 4 non-related blood donors with RHCE*cE (281C, 282T) variant allele (donors 1-4) were selected as the study objects. They donated blood at Shenzhen Blood Center from January 2022 to June 2023. The 4 blood donors were all Han. And 5 mL elbow venous blood was collected from these 4 blood donors. Regular serological assaying with 4 kinds of monoclonal antibody reagents was used for determination of the RhCcEe type. The nucleotide sequences of all 10 exons and adjacent flanking intron regions of RHCE gene in these 4 donors were analyzed by Sanger sequencing, and the full-length haplotype analysis of RHCE gene was performed by using the single-molecule real-time sequencing (SMRT) third-generation technology. DeepTMHMM software was used to analyze the structure of protein transmembrane region of wild type and variant RhCcEe protein and predict the location of amino acid substitution. The effects of mutations on RhCcEe protein function were analyzed using PolyPhen-2, SIFT and Mutation Taster bioinformatics software. Robetta and Swiss-PdbViewer v4.1.0 were used for modeling the tertiary structures of RhCcEe to analyze the difference between wild type and variant RhCcEe protein. The mutation was rated according to the standards and guidelines for the classification of genetic variants of the American College of Medical Genetics and Genomics (ACMG). This study has been approved by the Medical Ethics Committee of Shenzhen Blood Center (Approval No. SZBCMEC-2022-024).

Results: The RhCcEe phenotypes of the 4 blood donors were CCEweake by serological assaying. The RhE antigen were weakly expressed form 0 to 3+. The analysis of RHCE gene sequence indicated that all the 4 donors with RHCE*cE (281C, 282T) allele. The mutation caused the substitution of a single amino acid in the RhCcEe protein (p.Leu94 Pro) and the amino acid substitution was located in the transmembrane α3 chain resulted in significant changes in the 3D structure of the extracellular region of RhCcEe protein. The substitution was predicted to be "Probably damaging", "Damaging" and "Polymorphism" by PolyPhen-2, SIFT and Mutation Taster bioinformatics software. According to the guidelines of ACMG, the variant was rated to be likely pathogenic.

Conclusion: The RHCE*cE (281C, 282T) variant allele was first found in the Han Chinese population. The serological data of this allele were enriched. It provides an important guarantee for the safety of blood transfusion. Bioinformatics analysis provided evidences for further study of the structure and functions of RhCcEe protein.