ABO血型基因变异体引起正反定型不合1例

A Case Report of Forward/Reverse Blood Grouping Discrepancy Resulting from ABO Gene Variant

目的采用分子生物学技术分析ABO血型鉴定正反定型不合1例,为保障患者的输血安全提供依据。方法 ABO血型血清学鉴定采用微柱凝胶法。提取全血DNA,用序列特异性引物聚合酶链反应(PCR-SSP)进行ABO基因分型;用PCR法扩增ABO基因1~7号外显子进行直接测序,测序结果与A101序列进行比较。结果患者血型表现为正反定型不符,正向鉴定为O型,反向鉴定仅发现有抗-B凝集素,结果为A型。患者红细胞和抗-AB单克隆抗体有微弱的凝集。ABO PCRSSP基因分型表明患者为杂合O1/A基因型,进一步对外显子扩增测序发现ABO第6外显子存在248A>G误义突变,导致糖基转移酶83位天冬氨酸被甘氨酸替代(Asp83Gly)。用自行设计的引物采用PCR-SSP法对350例献血者进行248A>G突变频率调查,未发现阳性。结论 ABO基因248A>G变异体和缺乏抗-A凝集素以及A抗原极低水平表达相关。

Objective To analyze a discrepancy in results of forward/reverse ABO blood grouping with molecular analysis and provide knowledge for safe blood transfusion. Methods Column gel testing was used for serological ABO blood grouping. Genomic DNA was extracted from whole blood and PCR-SSP was used for ABO genotyping. PCR was performed to amplify ABO exons 1 to 7 and the amplification products were sequenced directly. The obtained sequences were compared with wild type A1 01 to identify sequence variation. Results Blood grouping indicated the discrepant results of forward/reverse ABO typing. Forward typing produced blood group O, while reverse typing produced blood group A as only anti-B isoagglutinins were present. A monoclonal anti-AB antibody detection revealed a weak agglutination with patient＇s RBCs. ABO genotyping with PCR-SSP indicated a heterozygous 01/A type,and further PCR and ABO exons sequencing identified a new 248A〉G missense mutation in exon 6, which led to the replacement of Aspartate at position 83 with glycine. PCR-SSP using newly designed 248 A〉G mutation-specific primer was performed to investigate the frequency of this new mutation among regular blood donors but none turned out to be positive. Conclusions This ABO gene 248A〉G mutation is associated with the absence of anti-A isoagglutinins and weak A antigen expression.