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目的对5个遗传性血小板无力症(GT)家系进行临床特征分析及基因突变检测,以探索其发病机制。方法通过出血病史、家族史调查,止血和凝血指标检测,血小板聚集实验和流式细胞术检测血小板表面整合素αⅡbβ3表达情况明确5个GT家系的诊断,并用PCR扩增结合直接测序法分析先证者及家系成员的整合素αⅡb基因和β3基因的所有外显子及其侧翼序列,突变位点经检索SNP数据库及查找相关文献排除多态性可能。结果 5个GT家系先证者血小板计数基本正常,凝血象正常,血小板对诱导剂二磷酸腺苷(ADP)反应低下,而对诱导剂瑞斯托霉素反应基本正常;流式细胞术检测结果显示:先证者一为变异型GT,先证者二为Ⅱ型GT,其余3个先证者均为Ⅰ型GT。基因分析共发现1例杂合突变及4例纯合突变:发生在αⅡb基因的4种突变分别为1652C>T(551Arg>Gln)、2671C>T(891Gln>stop)、2870C>T(957Ser>Leu)、2893-2897insC,发生在β3基因的2种突变分别为1199G>A(400Cys>Tyr)、1574G>A(525Gly>Asp)。结论β3 1199G>A纯合突变是家系一先证者发生GT的原因;β3 1574G>A纯合突变是家系二先证者发生GT的原因;αⅡb 1652C>T纯合突变是家系三先证者发生GT的原因;αⅡb 2671C>T(891Gln>stop)纯合突变是家系四先证者发生GT的原因;αⅡb 2870C>T(957Ser>Leu)、2893-2897insC双重杂合突是家系五先证者发生GT的原因。其中2671C>T(891Gln>stop)、2870C>T(957Ser>Leu)和2893-2897insC这3种突变为首次报道发生于αⅡb基因的突变,1574G>A(525 Gly>Asp)为首次报道发生于β3基因的突变。
Objective To investigate the clinical features and gene mutation in five hereditary platelet disorders (GT) pedigrees to explore their pathogenesis. Methods The diagnosis of 5 GT families was confirmed by the history of hemorrhage, family history, hemostasis and coagulation index, platelet aggregation test and flow cytometry to detect the expression of integrin αⅡbβ3 on platelet surface. PCR amplification combined with direct sequencing And family members of integrin α Ⅱ b gene and β3 gene all exons and flanking sequences, mutation sites by searching SNP database and find relevant literature to rule out the possibility of polymorphism. Results Five GT pedigree probands had normal platelet counts, normal clotting, low platelet response to ADP, and normal response to ristocetin. The results of flow cytometry Show: proband one variant GT, proband two Ⅱ type GT, the remaining three proband are type Ⅰ GT. One heterozygous mutation and four homozygous mutations were found in the gene analysis. The four mutations in the αⅡb gene were 1652C> T (551Arg> Gln), 2671C> T (891Gln> stop), 2870C> T (957Ser> Leu) and 2893-2897insC. The two mutations in the β3 gene were 1199G> A (400Cys> Tyr) and 1574G> A (525Gly> Asp), respectively. CONCLUSION: The homozygous mutation of β3 1199G> A is the cause of GT occurrence in a progenitor family. The homozygous mutation of β3 1574G> A is the cause of GT in the second progeny of family pedigree. The homozygous mutation of αⅡb 1652C> T is a The reason of occurrence of GT is that the homozygous mutation of αⅡb 2671C> T (891Gln> stop) is the cause of GT in the four family members of the pedigree. The double heterozygote of αⅡb 2870C> T (957Ser> Leu) and 2893-2897insC The reason for the occurrence of GT. Three mutations (2671C> T (891Gln> stop), 2870C> T (957Ser> Leu) and 2893-2897insC were the first reported mutations in the αⅡb gene. The first report of 1574G> A (525 Gly> Asp) β3 gene mutation.