目的:分析一个遗传性抗凝血酶缺乏症中国家系的临床表型和遗传特征。
方法:温州医科大学附属第二医院诊断的家系,玉英儿童医院六月,2020年被选为研究对象。血浆凝血酶原时间(PT),活化部分凝血活酶时间(APTT),纤维蛋白原(FIB),使用STA-R自动凝血分析仪确定先证者及其谱系成员的凝血酶时间(TT)。用显色底物和免疫比浊法测定血浆中的抗凝血酶活性(AT:A)和抗凝血酶抗原(AT:Ag)。通过PCR扩增抗凝蛋白基因SERPINC1的所有外显子和侧翼序列,并进行Sanger测序。候选变体用生物信息学工具(PolyPhen-2,SIFT,突变Taster和PYMOL),以探讨它们对蛋白质功能和结构构象的影响。
结果:先证者(II-2,II-10),他们的兄弟(II-5)和儿子(III-1,III-8)表现出正常的PT,APTT,FIB,而TT,但显着降低AT:A和AT:Ag,他们的水平是34%,57%,56%,48%,53%和13.51mg/dL,13.44mg/dL,18.39mg/dL,17.36mg/dL,17.71mg/dL,分别。其余谱系成员具有正常值。Sanger测序显示,先证者和所有受影响的谱系成员都具有杂合的c.851T>C(p。Met284Thr)SERPINC1基因外显子5的错义变异。生物信息学分析和模拟表明,该变体导致了在c.851位置的氢键的改变,这可能会影响蛋白质的结构。根据美国医学遗传学和基因组学学院(ACMG)的指南,该变异体被分类为致病性(PS1+PM1+PM5+PP1+PP4).
结论:先证者和其他受影响的成员都被诊断为I型遗传性AT缺乏症,其中c.851T>C(p.SERPINC1基因的Met284Thr)变体可能负责。
OBJECTIVE: To analyze the clinical phenotype and genetic characteristics of a Chinese pedigree affected with Hereditary antithrombin deficiency.
METHODS: A pedigree diagnosed at the the Second Affiliated Hospital of Wenzhou Medical University, Yuying Children\'s Hospital in June, 2020 was selected as the study subject. Plasma prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FIB), and thrombin time (TT) of the probands and their pedigree members were determined using a STA-R automatic coagulation analyzer. Antithrombin activity (AT: A) and antithrombin antigen (AT: Ag) in plasma were determined with chromogenic substrate and immunonephelometry assays. All exons and flanking sequences of the anticoagulant protein gene SERPINC1 were amplified by PCR and subjected to Sanger sequencing. Candidate variants were verified with bioinformatic tools (PolyPhen-2, SIFT, Mutation Taster and PYMOL) to explore their effect on the function and structural conformation of the protein.
RESULTS: The probands (II-2, II-10), their brother (II-5) and sons (III-1, III-8) had shown normal PT, APTT, FIB, and TT, but significantly decreased AT: A and AT: Ag, with their levels being 34%, 57%, 56%, 48%, 53% and 13.51 mg/dL, 13.44 mg/dL, 18.39 mg/dL, 17.36 mg/dL, 17.71 mg/dL, respectively. The remaining pedigree members had normal values. Sanger sequencing revealed that the probands and all affected pedigree members had harbored a heterozygous c.851T>C (p.Met284Thr) missense variant in exon 5 of the SERPINC1 gene. Bioinformatic analysis and simulation suggested that the variant has resulted in alteration of hydrogen bonds at the c.851 position, which may affect the structure of the protein. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as pathogenic (PS1+PM1+PM5+PP1+PP4).
CONCLUSIONS: The probands and other affected members were all diagnosed with type I hereditary AT deficiency, for which the c.851T>C (p.Met284Thr) variant of the SERPINC1 gene may be accountable.