一例Bw14亚型的鉴定及其分子机制的研究

Identification of a Bw14 subtype and exploration for its molecular basis

目的对1例罕见的ABO亚型进行鉴定并探讨其分子机制。方法在标准血型血清学方法鉴定的基础上，应用PCR方法扩增患者AB0基因7个外显子和侧翼内含子及克隆测序等方法进行ABO亚型的基因分型和单倍型分析。结果患者常规卡式法ABO正定型为B型，反定型有极弱的抗-B抗体，表现为正反定型不符；吸收放散实验证明患者红细胞表面不存在A抗原；AB0基因测序发现其第7外显子523位碱基发生G〉A突变，导致175位缬氨酸（VaI）被甲硫氨酸（Met）替换；ABO基因扩增产物测序及克隆测序结果表明该患者ABO血型基因型为ABO＊Bw14／001。结论分子生物学方法是鉴定疑难血型的必要方法。ABO基因的523G〉A突变可能是导致该Bw14亚型的B抗原表达减弱的分子遗传学基础之一。

Objective To identify a rare subtype of the ABO blood group system and explore its molecular basis. Methods Based on a standard serological assay, ABO subtype and haplotype were analyzed through PCR amplification of the 7 exons and adjacent introns of the ABO gene and TA clone sequencing. Results Forward typing showed a B type, while reverse typing demonstrated an extremely weak anti-B on routine gel analysis, which indicated a forward and reverse typing discrepancy. Abs＇orption- elution testing confirmed that there was no A antigen on the surface of patient＇s red blood cells. Sequencing of the ABO gene showed a G〉A exchange at position 523 in exon 7, which resulted in a Val to Met substitution at codon 175. Clone sequencing of the amplificons of the ABO gene showed an ABO＊ Bw14/ O01 heterozygote genotype. Conclusion Molecular method is useful for the identification of ambiguous blood groups. A 523G〉A substitution of the ABO gene resulting in a Bw14 subtype probably underlies the weak B phenotype noted in the patient.