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目的对 1 例遗传性抗凝血酶(AT)缺陷症患者及其家系成员 AT 活性(AT:A)、AT 抗原含量(AT:Ag)进行检测及基因分析,探讨该遗传性 AT 缺陷症发病的分子机制。方法采用发色底物法和免疫比浊法分别检测先证者及其家系成员血浆 AT:A 和 AT:Ag,提取外周血基因组 DNA,PCR法扩增 AT 基因的全部7个外显子及侧翼序列,DNA 序列分析 AT 的基因异常。结果先证者 AT:A和 AT:Ag 分别为45%和97 mg/L,为Ⅰ型 AT 缺陷症。AT 基因外显子5区第9833位核苷酸发生杂合性 T→A突变,引起 Tyr363Stop(Y363X)无义突变。其他家系成员基因测序结果显示有4人(Ⅱ2、Ⅱ6、Ⅲ7、Ⅲ14)存在该突变。结论该家系为Ⅰ型遗传性 AT 缺陷症 AT 基因外显子5区杂合性9833 T→A无义突变引起 AT 缺陷,导致静脉血栓是该遗传性 AT 缺陷症的分子致病机制。该突变在国际上尚未见报道。
Objective To detect and analyze the AT activity (AT: A), AT antigen (AT: Ag) in one case of hereditary anti-thrombin (AT) Molecular mechanism. Methods The chromosomal substrate method and immunoturbidimetric method were used to detect the plasma AT: A and AT: Ag in probands and their family members, respectively. Genomic DNA was extracted from peripheral blood and all seven exons of AT gene were amplified by PCR. Flanking sequence, DNA sequence analysis of AT gene abnormalities. Results The probands AT: A and AT: Ag were 45% and 97 mg / L, respectively, as type Ⅰ AT deficiency. The heterozygous T → A mutation occurs at the 9833th nucleotide in the exon 5 of AT gene, resulting in a nonsense mutation in Tyr363Stop (Y363X). Four other members (Ⅱ2, Ⅱ6, Ⅲ7, Ⅲ14) were found to have this mutation in other family members. Conclusion This pedigree is a type Ⅰ hereditary AT deficiency AT gene exon 5 heterozygous 9833 T → A nonsense mutations cause AT defects, leading to venous thrombosis is the molecular pathogenesis of hereditary AT deficiency. This mutation has not been reported in the world.