一种导致遗传性凝血因子Ⅻ缺陷症的FⅫ基因新突变  

Identification of a novel mutation of factor Ⅻ gene in a family with coagulation FⅫ deficiency

作　　者：谢海啸[1] 吕美艳[1] 杨小丽[1] 朱丽青[1] 杨丽红[1] 金艳慧[1] 王明山[1] 

机构地区：[1]浙江省温州医学院附属第一医院实验诊断中心,325000

出　　处：《中华医学遗传学杂志》2013年第3期313-317,共5页Chinese Journal of Medical Genetics

基　　金：基金项目：温州市科技计划资助项目（Y20L00208,Y20110074）

摘　　要：目的探讨一个遗传性凝血因子Ⅻ（coagulationfactorⅫ，FⅫ）缺陷症家系的发病机制。方法对先证者及其家系成员的活化部分凝血活酶时间（activatedpartialthromboplastintime，APTT）、血浆FⅫ活性（FⅫprocogulantactivity，FⅫ：C）和血浆FⅫ抗原（FⅫantigen，FⅫ：Ag）等进行表型诊断。用PCR技术对FⅫ基因的14个外显子及其侧翼序列进行扩增和测序。构建F河基因突变体，瞬时转染COS7细胞，测定表达产物的FⅫ：C的活性和FⅫ：Ag含量。结果先证者APTT明显延长至108．1s（正常参考值为27．0～41．0s），其丈夫APTT在正常范围，儿子、女儿和外孙的APTT轻度延长。先证者FⅫ：C和FⅫ：Ag均极度降低至0．01（正常参考值为0．72～1．13），其丈夫、儿子、女儿和外孙的FⅫ：C分别为0．57、0．24、0．14、0．16；FⅫ：Ag分别为0．55、0．27、0．15、0．21。先证者和女儿FⅫ基因第9外显子均发现g．6800—6808del9bp杂合型缺失突变。先证者及儿子、女儿、外孙F皿启动子区46C／T多态性均为TT基因型，丈夫为CT型。体外表达结果显示，突变体在细胞裂解液中FⅫ：Ag水平接近野生型，而在细胞培养上清液中的突变体FⅫ：Ag、FⅫ：C水平降至野生型的一半。结论该遗传性凝血因子Ⅻ缺陷症家系的先证者FⅫ基因第9外显子g．6800—6808del9bp为一新发现的突变。突变蛋白在细胞内大量蓄积，但存在分泌障碍。g．6800—6808del9bp和46T／T与FⅫ水平的降低有关，但不是先证者FⅫ水平极度降低的唯一原因。Objective To analyze genetic mutation and molecular pathogenesis in a family affected with inherited coagulation factor Ⅻ （F Ⅻ ） deficiency. Methods Activated partial thromboplastin time （APTT）, F~ procoagulant activity （F）~ = C）, FⅫ antigen （FⅫ . Ag） and other coagulants were measured. For affected members of the family, exons 1-14 and flanking intronic regions of the FⅫ gene were amplified with polymerase chain reaction （PCR） and sequenced thereafter. Expression plasmids containing mutant FⅫ cDNA was constructed and transfected into COS7 cells transiently. Expressions of FⅫ = Ag and FⅫ： C were analyzed. Results The proband has manifested a prolonged APTT of 108. 1 s （reference range： 27.0-41.0 s）. Her husband has a normal APTT. Other members of the family had slightly increased APTT. The FⅫ= C and FⅫ ： Ag of the proband have both dropped to about 0.01 （reference range： 0.72- 1.13）. The FⅫ： C levels of her husband, son, daughter and grandchild were 0.57, 0.24, 0. 14, 0. 16, respectively. And the FⅫ = Ag levels in her husband, son, daughter and grandchild were 0. 55, 0. 27, 0.15, 0. 21, respectively. The proband and her daughter have both carried a heterozygous deletional mutation 6800-6808delAGCTGGGAG （6800-6808de19bp） in exon 9. For the promoter region of the FⅫ gene, the genotypes of the proband, her son, daughter and grandchild was TT, whilst that of her husband was CT. Expression study has shown that, whilst the mutant FⅫ protein has accumulated in the cells similar to wild-type protein, its secretion has reduced approximately by half. Conclusion A novel deletional mutation 6800-6808delgbp has been identified in the FⅫgene. Although mutant FⅫprotein can still accumulate in cells, its secretion has become insufficient. The 6800-6808de19bp mutation and 46T/T have both contributed to the pathogenesis of FⅫ deficiency in the family, but may have not been the sole cause.

关 键 词：凝血因子Ⅻ 聚合酶链反应 FⅫ基因 突变体 

分 类 号：R440[医药卫生—诊断学] R596[医药卫生—临床医学]