Department of Transfusion Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China.
Department of Blood Transfusion, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou, Guangdong, China.
Transfus Med. 2024 Oct;34(5):445-449. doi: 10.1111/tme.13072. Epub 2024 Aug 1.
The Rh blood group antigens are encoded by the RHD and RHCE genes, which possess a remarkable degree of polymorphism owing to their high homologous structures. These variants of the RH genes can lead to absence or weak expression of antigens.
Analysis of RHCE genotyping by Polymerase Chain Reaction (PCR-SSP) method specific to detect c.48G, c.48C, 109 bp insertion of IVS2, c.201A and c.307C and RhCE phenotyping, were conducted in 316 Chinese patients in previous study. One patient with discrepancy typing result was collected for further RhCE serologic typing using microcolumn gel method and tube method in saline using monoclonal antibodies. PacBio sequencing was performed for RHCE, RHD and RHAG complete sequence analysis. 3D molecular models of the protein with the wild-type and mutant residue were generated using the DynaMut web server. The effect of the mutation on the protein function was predicted by PolyPhen-2 software.
One male patient of Chinese Han was detected with RHCEC allele showed by PCR-SSP method but ccEE phenotype. Further PacBio sequencing identified one normal RHCEcE allele and one RHCE*Ce allele carried a novel c.829G > A (p.Gly277Arg) variant, which the encoded amino acid located in the ninth transmembrane segment of RhCE protein. Crystallisation analysis of 3D molecular models revealed that the substitution at Arg277 leads to the formation of additional hydrogen bonds, including weak hydrogen bonds between multiple atoms. It also results in hydrophobic ion interactions between Arg277 and Ala244. This mutation is predicted to have a damaging effect on protein function.
One novel RHCE*Ce allele with c.829G > A (p.Gly277Arg) variant was identified to resulting in the absence or weak expression of C and e antigens.
Rh 血型抗原由 RHD 和 RHCE 基因编码，由于其高度同源的结构，这些基因具有显著的多态性。这些 RH 基因的变体可导致抗原缺失或弱表达。
在之前的研究中，通过聚合酶链反应（PCR-SSP）方法对 316 例中国患者进行了 RHCE 基因分型分析，该方法特异性检测 c.48G、c.48C、IVS2 中的 109bp 插入、c.201A 和 c.307C，以及 RhCE 表型。收集了一位与分型结果不符的患者，进一步采用微柱凝胶法和盐水试管法对 RhCE 进行血清学定型，使用单克隆抗体。对 RHCE、RHD 和 RHAG 进行完整序列分析。利用 DynaMut 网络服务器生成具有野生型和突变残基的蛋白质 3D 分子模型。利用 PolyPhen-2 软件预测突变对蛋白质功能的影响。
通过 PCR-SSP 方法检测到一名中国汉族男性患者为 RHCEC 等位基因，但表现为 ccEE 表型。进一步的 PacBio 测序鉴定出一个正常的 RHCEcE 等位基因和一个 RHCE*Ce 等位基因携带一个新的 c.829G > A（p.Gly277Arg）变体，该变体位于 RhCE 蛋白的第九个跨膜段的编码氨基酸。3D 分子模型的结晶分析表明，Arg277 的取代导致形成额外的氢键，包括多个原子之间的弱氢键。它还导致 Arg277 和 Ala244 之间的疏水离子相互作用。该突变被预测对蛋白质功能有损害作用。
鉴定出一个新的 RHCE*Ce 等位基因，携带 c.829G > A（p.Gly277Arg）变体，导致 C 和 e 抗原缺失或弱表达。
