儿童重型遗传性血管性血友病2例临床分析

Severe hereditary von Willebrand disease in children:a repert of 2 cases and clinical analysis

目的分析儿童重型遗传性血管性血友病(VWD)的临床特征及基因变异。方法回顾分析2例VWD患儿的临床资料,采用免疫比浊法检测血管性血友病因子(VWF)活性。采集患者及其父母的外周血,通过高通量基因测序,分析F7、F8、F9、F11、VWF基因全部外显子编码区和剪接区的变异情况。采用PCR结合Sanger测序的方法,分析VWF基因位点的变异情况。结果2例男性患儿,分别为1岁和2岁,临床表现以皮肤黏膜出血为主,血管性血友病因子活性(VWF:Act)分别为<5.0%及<2.8%。例1血浆因子Ⅷ凝血活性(FⅧ:C)1.9%、血浆因子ⅩⅡ凝血活性(FⅩⅡ:C)43.2%;例2 FⅧ:C 23%。例1 VWF基因检测到c.813C>G(p.Tyr271Ter)纯合变异;父母均为杂合变异。例2 VWF基因检测到c.55G>A(p.Gly 19 Arg)和c.1200 C>A(Asp400 Glu)杂合变异,分别来自其父亲、母亲。c.813C>G(p.Tyr 271Ter)变异与3型VWD相关;c.55G>A(p.Gly 19 Arg)变异率极低,与1型VWD相关;c.1200 C>A(Asp400 Glu)变异未见报道,SIFT、Polyphen和MutationTaster均预测其有致病性。2例患儿经止血及替代治疗后,病情均有所好转。结论经基因检测确诊重型1型和3型VWD各1例,并发现VWF基因c.1200 C>A(Asp400 Glu)新发变异。

Objective To explore the clinical characteristics and gene variation of severe hereditary von Willebrand disease(VWD)in children.Methods The clinical data of VWD in 2 children were retrospectively analyzed.The activity of von Willebrand factor(VWF)was detected by immunoturbidimetry.Peripheral blood samples were collected from the patients and their parents.High-throughput gene sequencing was performed to analyze the variation of all exon coding regions and splicing regions of F7,F8,F9,F11 and VWF genes.The variation of VWF gene locus was analyzed by PCR combined with Sanger sequencing.Results Two boys,aged 1 and 2 years respectively,were clinically characterized by mucocutaneous hemorrhage,and the von Willebrand factor activity(VWF:Act)was<5.0%and<2.8%,respectively.In case 1,the coagulation activity of plasma factorⅧ(FⅧ:C)was 1.9%,and the coagulation activity of plasma factorⅫ(FⅫ:C)was 43.2%.The FⅧ:C in case 2 was 23%.A homozygous variation of c.813C>G(p.Tyr271Ter)was detected in VWF gene of case 1;both of his parents were heterozygous variation.In case 2,heterozygous variations of c.55G>A(p.Gly19 Arg)and c.1200 C>A(Asp400Glu)were detected in VWF gene,which came from his father and mother,respectively.The c.813C>G(p.Tyr271Ter)variation was associated with type 3 VWD.The mutation rate of c.55G>A(p.Gly19 Arg)was extremely low and was related to type 1 VWD.The mutation of c.1200 C>A(asp400glu)has not been reported,but the software SIFT、Polyphen and MutationTaster all predicted its pathogenicity.Both patients improved after hemostasis and replacement therapy.Conclusion One case of severe type 1 VWD and one case of severe type 3 severe type 1 VWD were confirmed by gene testing.A new mutation 1200 C>A(Asp400Glu)in VWF gene was found.