Cheng Xiaoli, Yang Lihong, Huang Guoyong, Jin Yanhui, Hao Xiuping, Wang Mingshan
a Department of Clinical Laboratory , The First Affiliated Hospital of Wenzhou Medical University , Wenzhou , China.
Hematology. 2017 Jun;22(5):310-315. doi: 10.1080/10245332.2016.1265210. Epub 2016 Dec 22.
To study the gene mutations of factor XII (FXII) in a Chinese family of consanguineous marriage with FXII deficiency and illuminate the possible molecular pathogenic mechanism. It will contribute to our comprehension of the pathogenesis of the disease.
The proband was a 26-year-old Chinese pregnant woman who was discovered, in a pregnancy test, with a prolonged activated partial thromboplastin time (APTT) at 61.6s (reference range, 29.0-43.0s).
The FXII activity (FXII:C) and FXII antigen (FXII:Ag) were tested with clotting assay and ELISA, respectively. The FXII gene (F12) was amplified by PCR with direct sequencing. A ClustalX-2.1-win and four online bioinformatics software (PolyPhen-2, PROVEAN, SIFT, and Mutation Taster) were used to study the conservatism and harm of the mutation. The reference range of each test indicator in our laboratory was established with 150 healthy subjects. Conclusion headings: The FXII:C and FXII:Ag of the proband were 12% and 10% (normal range, 72-113%), respectively. Gene sequencing detected a homozygous c.1078G > A point mutation in exon 10 resulting in a substitution of glycine 341 by arginine (Gly341Arg) in the proline-rich domain of FXII. Family study showed that her elder brother had the same phenotype and genotype with her. In addition, there were another six heterozygous members in her family. Both conservatism and bioinformatics results indicated the mutation probably had affected the function of the protein. We thought the Gly341Arg mutation was responsible for the decreased activity of FXII:C and FXII:Ag. And in vitro expression experiment is performed to elucidate the precise pathological mechanism of the mutation.
研究一个患有因子Ⅻ（FXII）缺乏症的中国近亲结婚家族中FXII的基因突变情况，并阐明可能的分子致病机制。这将有助于我们理解该疾病的发病机制。
先证者是一名26岁的中国孕妇，在孕期检查中发现活化部分凝血活酶时间（APTT）延长至61.6秒（参考范围为29.0 - 43.0秒）。
分别采用凝血试验和酶联免疫吸附测定（ELISA）检测FXII活性（FXII:C）和FXII抗原（FXII:Ag）。通过聚合酶链反应（PCR）扩增FXII基因（F12）并进行直接测序。使用ClustalX - 2.1 - win和四个在线生物信息学软件（PolyPhen - 2、PROVEAN、SIFT和Mutation Taster）研究突变的保守性和危害性。我们实验室以150名健康受试者建立了各检测指标的参考范围。结论部分：先证者的FXII:C和FXII:Ag分别为12%和10%（正常范围为72 - 113%）。基因测序检测到外显子10存在纯合的c.1078G＞A点突变，导致FXII富含脯氨酸结构域中的甘氨酸341被精氨酸替代（Gly341Arg）。家系研究表明，她的哥哥与她具有相同的表型和基因型。此外，她的家族中还有另外6名杂合成员。保守性分析和生物信息学结果均表明该突变可能影响了蛋白质的功能。我们认为Gly341Arg突变是导致FXII:C和FXII:Ag活性降低的原因。并且进行了体外表达实验以阐明该突变的确切病理机制。
