新的突变导致ACTN1相关血小板减少症的家系研究  

Pedigree Analysis of ACTN1-Related Thrombocytopenia Attributed to A Novel Mutation

作　　者：刘建新 王春键 戴菊华 张梅香[1] 吕萌[3] 孙于谦[3] 江滨 LIU Jian-Xin;WANG Chun-Jian;DAI Ju-Hua;ZHANG Mei-Xiang;LYU Meng;SUN Yu-Qian;JIANG Bin(Depariment of HematologyPeking University Intemational Hospital,Beijing 102206,China;Depariment of Clinical Laboratory Examination,Peking University Intemational Hospital,Beijing 102206,China;Departmentof Hematology,Peking University Peoples Hospital,Peking University Instituteof Hematology,Beijing 100044,China)

机构地区：[1]北京大学国际医院血液科,北京102206 [2]北京大学国际医院检验科,北京102206 [3]北京大学人民医院血液科、北京大学血液病研究所,北京100044

出　　处：《中国实验血液学杂志》2022年第2期565-570,共6页Journal of Experimental Hematology

摘　　要：目的:对1个ACTN1相关血小板减少症家系进行临床表型和基因型研究,并探讨其分子发病机制。方法:抽取全部家系成员外周血,检测血常规、血涂片、凝血功能、血小板聚集试验。流式细胞术检测血小板CD41和CD61的表达。先证者及其父亲行骨髓细胞形态学检测。全外显子测序技术扩增血小板型出血障碍相关基因所有外显子及其侧翼序列,PCR产物纯化后直接测序进行基因分析。采用生物信息学软件评估突变位点保守性、危害性;采用分子结构模拟图分析预测突变氨基酸对α-肌动蛋白-1结构和功能的影响。结果:先证者血小板数88×10^(9)/L,血涂片可见哑铃状血小板、蛇形血小板及血小板大小不等;骨髓细胞形态学:巨核细胞形态正常,计数270个。先证者的父亲血小板数74×10^(9)/L,血涂片可见大血小板,血小板大小不等;骨髓细胞形态学:巨核细胞计数239个。先证者的祖父血小板数83×10^(9)/L,血涂片可见蛇形血小板、血小板大小不等。其余家系成员各项检测指标均正常。先证者ACTN1基因第20外显子c.2396G>A错义突变导致所编码蛋白质799位氨基酸Arg突变为His。先证者的父亲、祖父在该位点的测序结果均与先证者相同。生物信息学分析显示该位点在不同物种之间高度保守,该位点的变异可能导致蛋白功能损害;通过蛋白模型分析显示α-肌动蛋白-1 799位Arg与811位Glu形成临界盐桥,稳定钙调蛋白样基序内Ca;结合环的构象。R799H突变失去了这个关键的盐桥,使该结构域失稳态。结论:新发现的ACTN1基因第20外显子c.2396G>A错义突变是导致本研究家系血小板减少症发生的分子机制。Objective: To investigate the clinical phenotype and genotype of an ACTN1-associated thrombocytopenic family and explore its molecular pathogenesis. Methods: All the family members′ peripheral blood was collected for routine blood tests, blood smear, coagulation function, and platelet aggregation test. Flow cytometry was used to detect the expression of platelet CD41 and CD61. The proband and her father were tested bone marrow cytomorphology. Whole-exome sequencing techniques were performed to detect and uncover mutant loci of suspected pathogenic genes. Bioinformatics was used to assess the conserved nature of the mutated loci and to analyze the effect of the mutated genes leading to the function of the corresponding amino acid sequences. Results: The platelet count of the proband was 88×10^(9)/L, and the blood smear showed dumbbell-shaped platelets, snake-shaped platelets and platelets of various sizes. Her bone marrow cytomorphology revealed normal megakaryocyte morphology with a count of 270. The platelet count of the proband′s father was 74×10^(9)/L, with large platelets and platelets of various sizes observed in the blood smear, and the morphology of megakaryocytes was normal in bone marrow with a megakaryocyte count of 239. Her grandfather had a platelet count of 83×10^(9)/L, with snake-shaped platelets and platelets of various sizes on blood smears. Other family members were normal in all tests. The missense mutation c.2396 G > A in exon 20 of the ACTN1 gene in the proband resulted in the mutation of 799 amino acids of the encoded protein, i.e., Arg, to His. The sequencing results of her father and grandfather at this locus were found to be consistent with her. Furthermore, bioinformatics analysis indicated that the locus w as highly conserved across species and that variation in this locus might lead to functional impairment of the protein. The protein model analysis demonstrated that α-actin-1 at position 799 Arg and Glu at position 811 could form a critical salt bridge which stabilizes the conf

关 键 词：遗传性 ACTN1突变 血小板减少 

分 类 号：R558.2[医药卫生—血液循环系统疾病]