Objective To analyze FⅫ gene mutation and investigate the molecular mechanism of FⅫ in a Chinese pedigree with congenital FⅫ deficiency.Methods The plasma aPTT,FⅫ activity and FⅫ antigen were detected.The exons 1-14,boundary intmns including the splice junctions of FⅫ gene of the FⅫ deficiency Pedigree members were amplified by PCR The PCR products were purified and sequenced directly.The sequencing was perform with reverse primer if the gene mutations were found.One hundred healthy persons were used as normal controls.Results The proband and the younger brother manifested prolonged aPTT(79.1 s/35 s,84.6 s/35 s respectively).The aPTT result of the older son was 42.1 s/35 s.slightly higher than the normal level.The levels of other members were in normal range.The FⅫ activities of the proband and the younger brother were as low as 2% and 3% respectively,and the levels of FⅫantigen were <1%.The FⅫ activities of his older brother.the older and the younger son were 39%.29%,34% respectively.And the levels of FⅫ antigen were 32%,30%,37% respectively.In the promoter regions of FⅫ gene,the genotype of the proband and the younger brother was 46T/T.And in exon5 for the proband and the younger brother,there was mutations of 5741deleteC and 5742deleteA,resulting in Ser400Pro.And in exon10,there was an insertion mutation 7142insertC,resulting in one missense mutation Lys346Gln(K346Q).In the other members of the family,the older brother and the two sons harbored 46T/T and 7142insertC.And the little granddaughter had 46T/T and the geuotype of the niece and the two older granddaughters was 46C/T.Conclusions In the congenital factor Ⅻ deficiency pedigree,there was a common 46C→T polymorphism in promoter region of FⅫ gene.There was 5741deleteC and 5742deleteA in exon 5 and 7142insertC in exon 10.The mutations of 5741deleteC,5742deleteA and 7142insertC were attributed to decrease in the levels of Factor Ⅻ.%目的 对一个遗传性FⅫ缺陷症家系进行 FⅫ基因突变检测,探讨其参与的分子发病机制.方法 通过活化aPTT、FⅫ:C和FⅫ:Ag等测定进行表型诊断;用PCR技术对先证者及其家系成员FⅫ基因的14个外显子及其侧翼序列进行扩增,PCR产物纯化后,由DNA测序仪进行测序,发现突变位点则反向测序以证实.选择100名健康体检者作对照.结果 先证者及胞弟aPTT明显延长,分别为aPTT79.1s/35 s、aPTT 84.6 s/35 s,大儿子aPTT稍高,为42.1 s/35 s,家系其他成员aPTT正常范围.先证者及胞弟FⅫ:C极度降低,分别为2%、3%,其FⅫ:Ag水平均<1%;胞兄、大儿子和小儿子FⅫ:C明显下降,分别为39%、29%、34%,FⅫ:Ag水平分别为32%、30%、37%.先证者及胞弟FⅫ 1号外显子启动子区46位表现为46T/T型;5号外显子发现5741delc,5742delA,读码框移位,导致Set400Pro;10号外显子发现7142insertC,使得Lys346Gln终止密码子提前出现,产生截短蛋白.此外,家系其他成员:胞兄、大儿子及小儿子发现46T/T和7142insertC;小孙女发现46T/T;侄女、大孙女、二孙女发现46C/T.结论 在该遗传性FⅫ缺陷症家系发现常见的46C/T多态性及exon5区5741delC,5742delA与exon10区7142insertC.5741delC,5742delA及7142insertC与FⅫ水平的降低有关.
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