遗传性蛋白S缺陷症家系基因突变的研究

Investigation on gene mutation from hereditary protein S deficiency pedigree

目的 对2个遗传性PS缺陷症家系进行临床表型诊断和基因突变检测.方法 PS：A测定采用发色底物法;TPS：Ag、FPS;Ag测定采用ELISA法;PS基因（PROS1基因）检测采用PCR方法 对先证者PROS1基因的15个外显子及其侧翼内含子序列进行扩增,PCR产物纯化后直接测序.结果 先证者1的PS：A为48.6%,FPS：Ag为41 mg/L,TPS：Ag为136 mg/L,PROS1基因2号外显子在c.C121T位点发生杂合碱基替换,导致编码的PS蛋白存在Arg-1 Cys（R-1C）杂合错义突变.先证者2的PS：A为29.2%,FPS;Ag为26 mg/L,TPS：Ag为83 mg/L,PROSl基因14号外显子在c.C1687T位点发生杂合碱基替换,导致编码的PS蛋白存在Gln522Stop杂合无义突变.结论 c.C121T是PROS1基因的一个新的突变位点,该杂合突变可以导致Ⅱ型遗传性PS缺陷症;c.C1687T杂合突变导致Ⅰ型遗传性PS缺陷症.

Objective To identify the clinical phenotypic diagnosis and gene mutation detection of two kindreds with PS deficiency. MethodsPS： A was measured by chromogenic substrate method;TPS：Ag, FPS： Ag levels were measured by ELISA method; PS gene（PROS1 gene）was detected by amplifying 15 exons and flanking intron sequences from the propositus with PCR method. PCR products were purified and directly sequenced. Results For propositus 1,PS： A was 48.6% ,TPS： Ag was 136 mg/L, FPS ： Ag was 41 mg/L, PROSI gene exon 2 was in c. Heterozygous base substitutions was detected in C121T locus, which led to Arg-1Cys （R-1C） heterozygous roissense mutation encoded in PS proteins. For propositus 2, PS： A was 29.2%, TPS： Ag was 83 mg/L, FPS： Ag was 26 mg/L, PROSI gene exon 14 was in c. Heterozygous base substitutions was identified in CI687T locus, in which Gln.522Stop heterozygous nonsense mutation was encoded in PS proteins. Conclusions c. C121T is a novel mutation locus detected in PROS1 gene. This heterozygous mutation could lead to type Ⅱ PS hereditary deficiency, while c. C1687T heterozygous mutation could bring about type Ⅰ PS hereditary deficiency.