目的：探讨1个遗传性血管性血友病（von Willebrand disease,vWD）2N型家系的表型诊断和基因型分析结果,明确患者的发病机制。方法：对该家系的先证者和家系成员进行出血时间、活化部分凝血活酶时间、瑞斯托霉素诱导的血小板聚集（ristocetin induced platelet aggregation,RIPA）试验、血管性血友病因子（von Willebrand factor,vWF）瑞斯托霉素辅因子、vWF抗原、vWF活性测定、vWF胶原结合试验、凝血因子Ⅷ（coagulation factor Ⅷ,FⅧ）活性、vWF与FⅧ结合试验检测,并作出表型诊断。提取先证者的外周血基因组DNA,用PCR法扩增VWF基因和F8基因的所有外显子及侧翼序列,通过直接测序分析VWF基因和F8基因变异。结果：vWD家系先证者的活化部分凝血活酶时间和出血时间明显延长,血浆瑞RIPA试验、vWF瑞斯托霉素辅因子、vWF抗原、vWF活性和vWF胶原结合试验检测结果均正常,FⅧ活性下降,vWF与FⅧ的结合能力降低。对先证者进行基因测序,发现其VWF基因19号外显子存在c.2446C>T（p.Arg816Trp）错义突变,其儿子在该位点为杂合突变,而先证者及家系成员的F8基因未发现突变。结论：c.2446C>T（p.Arg816Trp）错义突变是导致该家系先证者发生2N型遗传性vWD的原因。
Objective: To analyze the phenotype and genotype of one Chinese pedigrees with von Willebrand disease and to investigate the molecular pathogenesis of the disease. Methods: Indices including bleeding time(BT), activated partial thromboplastin time (APTT), ristocetin-induced platelet aggregation(RIPA), von Willebarand factor-ristocetin cofactor (vWF:Rco), von Willebrand factor antigen (vWF:Ag), von Willebrand factor activity (vWF:Act), von Willebrand factor collagen binding assay (vWF:CB) and von Willebrand factor FⅧ binding assay (vWF: FⅧ:B) were detected for phenotype diagnosis. Peripheral blood DNA was extracted, and all of the exons and exon-intron boundaries of the VWF and F8 gene were amplified by polymerase chain reaction (PCR) and analyzed with direct sequencing. Results: The results revealed that APTT and BT of proband were prolonged while plasma RIPA, vWF:Rco, vWF:Ag, vWF:Act and vWF:CB were normal. FⅧ:C and vWF: FⅧ:B were significantly decreased. Homozygous missense mutation c.2446C>T (p.Arg816Trp) in exon 19 of VWF gene was identified in proband and heterozygous mutation was identified in his son. No mutation in F8 gene was found in proband. Conclusions: Homozygous missense mutation c.2446C>T (p.Arg816Trp) in exon 19 of VWF gene is the cause of 2N type von Willebrand disease in the proband.
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