摘要
目的:探讨一例遗传性凝血因子Ⅶ(coagulation factor Ⅶ,FⅦ)缺陷症家系基因突变的类型。方法:检测凝血指标以明确诊断;用DNA直接测序法对先证者及其家庭成员FⅦ基因的全部外显子和其侧翼以及启动子进行分析,寻找基因突变;将含突变序列克隆入pGEM T—easy质粒载体中,对所得两条染色体相应序列分别测序,以确定不同突变在染色体上的分布。应用限制性内切酶MspⅠ对先证者及家系成员相应基因片段进行酶切分析,证实测序所发现的突变。结果:先证者在8号外显子上有两种基因突变:11348位C→T突变和11349位G→A突变。pGEM T—easy质粒克隆测序结果显示上述两种突变位于不同的染色体上。为不同染色体同一编码区Arg(CGG)304Trp(TGG)和Arg(CGG)304Gln(CAG)双重杂合性突变。其父亲、母亲分别为11349位G→A和11348位C→T杂合突变;先证者的弟弟FⅦ基因为正常野生型;其哥哥和3个子女均为杂合性突变。PCR辅助限制性酶切证实了先证者及其家系成员的基因突变。结论:先证者FⅦ基因突变为不同染色体同一编码区Arg304Trp和Arg304Gln双重杂合性突变,此种突变类型的组合尚属首例。
objetive: To investigate the genotypes of mutations of an inherited coagulation factor Ⅶ (FⅦ) deficiency pedigree. Methods: The diagnosis was validated by coagulant parameters. FⅦ gene mutations were analysed in the proband and her family members by DNA direct sequencing. The PCR fragments were cleaved by the MspI restriction enzyme to confirm the mutations detected by sequencing. Results: Double heterozygous mutations at the same coding site of amino acid were detected in propositus of the pedigree: a C to T mutation at position 11348 resulting in Arg304Trp substitution combined with a G to A mutation at position 11349 resulting in Arg304Gln substitution. Her farther had a G to A mutation at position 11349 and her mother had a C to T mutation at position 11348, respectively. Both were heterozygous mutations. One of her brothers had normal genotype, the other one and all her three offsprings had heterozygous mutations. Conclutions: double heterozygous mutations coding the same amino acid were found in a pedigree with hereditary coagulation factor Ⅶ deficiency.
