α1,3-D-半乳糖基转移酶基因425C→T突变导致B3亚型分析
425C→T mutation of α1,3-D-galactose transferase gene responsible for B3 subtype

目的:探讨B3亚型及其家系成员的血型血清学特点及分子机制。方法:对B3亚型及其家系成员进行ABO血型血清学定型,血浆α1,3-D-半乳糖基转移酶活性测定,ABO基因第6、7外显子及其侧翼序列的PCR扩增,基因测序和克隆分析。结果:先证者血型血清学鉴定ABO血型为B3亚型,血浆中α1,3-D-半乳糖基转移酶活性<1,该家系中2份标本ABO基因序列与标准序列相比,在第7外显子存在c.425C→T的杂合突变,致α1,3-D-半乳糖基转移酶的第142位氨基酸由甲硫氨酸替换为苏氨酸,先证者ABO基因型为B305/O102,且能在家系中稳定遗传。结论:基因位点突变425C→T是导致B3亚型的分子遗传基础,DNA 测序能够阐述 ABO 血型亚型的分子机制及其稳定遗传特性。
Aim: To explore the characteristics of blood group serology and molecular mechanism of B3 subtype family members.Methods: The ABO blood group serological test, the activity determination of α1,3-D-galactose transferase in plasma,as well as PCR amplification, gene sequencing and cloning analysis in 6 and 7 exon of ABO genes and flanking sequence were carried out.Results: B3 subgroup was serologically identified, and the α1,3-D-galactose transferase activity was lower than 1 in plasma of the proband.Compared with standard sequence,there was a single mutation of C→T was identified at 425 position of exon 7 in the line of the ABO gene sequence of 2 specimens,and the 142 amino acid of α1,3-D-galactose aminotransferase,methionine,was replaced by threonine.The ABO genotype could be identified as B305/O102 and stable inherited in the family system.Conclusion: Gene point mutation 425C→T is the molecular genetic basis that causes B3 subtype. DNA sequencing could explain the molecular mechanism of ABO blood type subtype and its stable genetic characteristics