一例遗传性蛋白C缺陷症家系的实验诊断

目的对1例遗传性蛋白C缺陷症家系进行临床表型诊断和基因突变检测。方法用发色底物法测定血浆蛋白C活性;用聚合酶链反应（PCR）法对先证者PC基因（PROC）的9个外显子及其侧翼序列进行扩增,PCR产物纯化后直接测序,检测其基因突变。家系成员DNA在先证者PROC基因突变区域扩增后测序,进行家系调查以期发现遗传规律。结果先证者蛋白C活性为38.6%,抗原为45.3%。直接基因测序分析发现先证者PROC基因外显子7区存在杂合错义突变c.565C〉T,该突变将引起编码的蛋白C 147位精氨酸被色氨酸替换（p.Arg147Trp）。家系分析发现先证者的c.565C〉T突变遗传于其父亲。结论 c.565C〉T杂合突变是导致该家系遗传性PC缺陷症的原因。

Laboratory diagnosis of one pedigree with hereditary protein C deficiency

Objective To study the laboratory diagnosis of one pedigree with hereditary protein C deficiency.Methods The plasma levels of protein C activity were detected by chromogenic assay.All of the 9 exons and intron-exon boundaries of protein C gene（PROC） were amplified by direct sequencing after purifing the corresponding amplified polymerase chain reaction（PCR） products in DNA from the propositus,and the gene mutation was also detected.The genetic development was analyzed by the research of family members.Results The plasma concentrations of protein C activity of the propositus was 38.6%,and that of antigen was 45.3%.Gene analysis revealed that the propositus had a c.565CT heterozygous missense mutation at exon 7 of PROC gene,which would cause the amino acid substitution of Arg to Trp at position 147（p.Arg147Trp）.The pedigree analysis showed that c.565CT mutation was inherited from father.Conclusions The c.565CT heterozygous mutation leads to protein C hereditary deficiency for this pedigree.