特发性血小板减少性紫癜和系统性红斑狼疮患者血浆中血管性血友病因子裂解蛋白酶的测定

血管性血友病因子（vwF）裂解蛋白酶（ADAMTS13）是近年发现的调节vwF分子量大小的主要蛋白酶。ADAMTS13活性缺乏临床上可导致血栓性血小板减少性紫癜（TTP）的发生。Moore等报道特发性血小板减少性紫癜（ITP）、系统性红斑狼疮（SLE）等患者ADAMTS13活性也降低，为进一步明确ADAMTS13在ITP和SLE发病中的意义，我们用新近建立的试剂盒检测了上述患者ADAMTS13及vWF的抗原含量。     

ADAMTS-13活性水平检测在ITP与TTP鉴别中的意义

目的　探讨VWF裂解蛋白酶(ADAMTS -13,vWP cp)活性水平的检测在特发性血小板减少性紫癜(ITP)与血栓性血小板减少性紫癜(TTP)鉴别中的意义。方法　采用残余胶原结合实验(Residual CollagenBindingAssay)分别对35例ITP、6例TTP及32例健康人血浆ADAMTS 13活性水平进行检测。结果　ITP及TTP患者血浆ADAMTS 13活性水平[(47.6 2±2 4 . 2 2 ) %、(12 .5 4±11.6 9) % ]显著低于正常人[(78 .6 0±10 .0 3) % ](P <0 . 0 1) ,ITP患者血浆ADAMTS 13活性水平明显高于TTP患者(P<0. 0 1) ,ITP患者血浆ADAMTS 13活性水平阳性率[6 8 5 7% (2 4 /35 ) ]明显低于TTP患者[10 0 % (6 /6 ) ](P <0 . 0 1)。结论　ADAMTS 13活性水平检测在ITP与TTP鉴别诊断中具有一定的意义。     

1例新基因突变导致的Ⅰ型遗传性血色病报道

目的对1例临床诊断遗传性血色病基因的患者及家属成员的遗传性血色病相关蛋白(HFE)基因进行检测。方法检测患者及家属成员血清铁蛋白(SF),血清铁(SI)等水平,从外周血单个核细胞中提取DNA,多聚酶联反应(PCR)扩增Ⅰ(HFE,原发性血色病)、Ⅱ(HJV,青少年型血色病)、Ⅲ(TfR2,转铁蛋白受体2相关血色病)型遗传性血色病相关基因的25个外显子及外显子邻近处的内含子,直接测序检测突变。结果患者SF、SI、总铁结合力、未饱和铁明显升高。HFE基因第3号内含子5′端第5碱基处出现T→C错义突变(为纯合子,IVS3+5T→C)。其家属成员中还发现2例纯合子和4例杂合子。Ⅰ、Ⅱ、Ⅲ型外显子未发现突变。结论该突变可能是遗传性血色病发病的分子生物学基础。     

血栓性血小板减少性紫癜16例临床分析

目的分析16例血栓性血小板减少性紫癜（TTP）患者的临床资料,以提高临床的早期诊断率。方法收集2007年～2011年苏州大学附属第一医院临床诊断为TTP的住院患者资料共16例,分析其临床资料,包括首发症状、病程、临床特点、实验室检查、治疗及转归。结果16例患者均有溶血性贫血、血小板减少、神经系统损害表现,15例有发热,8例有肾功能不全。12例ADAMTS13活性明显降低,其中8例ADAMTS13抑制物阳性。15例患者进行了血浆置换,12例患者治愈或好转,有效率为80％。结论ADAMTS13活性及抑制物检测有利于TTP早期诊断,尽早开始血浆置换可改善预后。     

血栓性血小板减少性紫癜患者vWF裂解蛋白酶抗原和活性的检测及意义

目的研究血管性血友病因子裂解蛋白酶(ADAMTS13)抗原含量和活性在血栓性血小板减少性紫癜(TTP)患者及遗传性 TTP 家族突变携带者中变化的情况。方法用残余胶原结合实验(RCBA)检测13例 TTP 患者共28份血浆标本[含血浆置换(PE)前后]及10例携带者的 ADAMTS13活性;用新近建立的三抗体夹心酶联免疫反应法检测标本的 ADAMTS13抗原含量。结果正常对照组 ADAMTS13含量为(600.93±145.36)mU/ml(设白种人混合血浆的 ADAMTS13抗原含量为1000mU/ml),活性为(74.79±11.81)%。遗传性 TTP 患者 ADAMTS13抗原含量和活性治疗前和发病间期均明显减低,PE 后恢复;其家族中携带者 ADAMTS13抗原含量为(331.40±109.85)mU/ml,活性为(66.79±12.82)%(与对照组比较,P 值分别<0.01和>0.05);原发性 TTP 患者 PE 前 ADAMTS13抗原含量为(98.7±82.08)mU/ml,活性为(22.23±19.07)%(与对照组比较,P 值均<0.01);PE 后ADAMTS13 抗原含量为(449.4±232.33)mU/ml,活性为(60.92±22.33)%(与对照组比较,P 值分别<0.01和>0.05);1例继发性 TTP 患者 PE 后 ADAMTS13抗原含量远高于正常,活性仅为6.00%结论治疗前的 TTP 患者 ADAMTS13抗原含量和活性均明显减低。大多数患者两指标变化趋势一致,也有个别患者两指标变化趋势相反,前者可能因为遗传因素或体内免疫系统的廓清作用,后者可能因为抗 ADAMTS13抗体仅抑制了 ADAMTS13的活性而未影响其抗原的含量或其他未知原因所致。     

血管性血友病因子裂解蛋白酶活性的检测方法及评估

血管性血友病因子裂解酶（ADAMTS13，vWF—CP）裂解血浆中具有高黏附能力的超大分子量血管性血友病因子（UL—vWF），防止血小板因其引起聚集形成血栓。ADAMTS13活性异常是临床上血栓性血小板减少性紫癜（TTP），特别是遗传性TTP和特发性TTP发病的基础。其活性的检测在TTP临床诊断和治疗上具有日益重要的意义。目前报道的一些用于检测ADAMTS13活性的方法有十余种，本文对此进行综述。     

血管性血友病因子裂解蛋白酶活性的检测方法及评估

血管性血友病因子裂解酶(ADAMTS13,vWF-CP)裂解血浆中具有高黏附能力的超大分子量血管性血友病因子(UL-vWF),防止血小板因其引起聚集形成血栓。ADAMTS13活性异常是临床上血栓性血小板减少性紫癜(TTP),特别是遗传性TTP和特发性TTP发病的基础。其活性的检测在TTP临床诊断和治疗上具有日益重要的意义。目前报道的一些用于检测ADAMTS13活性的方法有十余种,本文对此进行综述。     

影响获得性血栓性血小板减少性紫癜首次缓解期内复发的相关指标研究

目的 探讨血管性血友病因子裂解蛋白酶(ADAMTS) 13活性和抗ADAMTS13抗体表达水平,与获得性血栓性血小板减少性紫癜(TTP)于首次缓解期内复发的关系.方法 选择2008年3月至2014年6月于陕西延安大学附属医院和陕西省渭南市富平县医院诊治的37例获得性TTP患者为研究对象,按照其在首次缓解随访期内是否复发,分为研究组(n=15)和对照组(n=22).分别采用残余胶原结合试验、ELISA、免疫印迹等方法,检测两组患者的ADAMTS13活性,ADAMTS13抗原水平,抗ADAMTS13抗体,ADAMTS13抑制物,血管性血友病因子(vWF)抗原和超大分子量vWF(ULVWF)多聚体等指标,并且进行统计学分析;采用多因素非条件logistic回归分析法,评估获得性TTP患者于首次缓解期内复发的独立影响因素.本研究遵循的程序符合病例收集医院人体试验委员会所制定的伦理学标准,得到该伦理会批准,分组征得受试对象本人的知情同意,并与之签订临床研究知情同意书.结果 ①研究组患者的中位ADAMTS13活性为11％(7％～124％),低于对照组的53％(7％～151％),差异有统计学意义(u=4.018,P＜0.05).研究组与对照组患者的ADAMTS13活性显著降低率分别为53.3％(8/15)和22.7％(5/22),二者比较,差异有统计学意义(P=0.049).②37例获得性TTP患者的血浆ADAMTS13活性和ADAMTS13抗原水平呈正相关关系(rs=0.810,P=0.001).研究组患者的中位ADAMTS13抗原水平为33％(3％～99％),低于对照组的59％(3％～128％),差异有统计学意义(u=4.121,P＜0.05).研究组与对照组ADAMTS13抗原水平显著降低率分别为13.3％(2/15)和9.1％(2/22),二者比较,差异有统计学意义(P=0.008).③研究组患者的抗ADAMTS13抗体检出率为66.7％(10/15),高于对照组的36.4％(8/22),差异有统计学意义(P=0.007).④研究组患者中抗ADAMTS13抑制物检出率为46.7％ (7/15),高于对照组患者的18.2％ (4/22),差异有统计学意义(P=0.011).⑤研究组与对照组患者ULVWF多聚体检出率分别为20.0％(3/15)和13.6％(3/22),二者比较,差异有统计学意义(P=0.042).⑥多因素非条件logistic回归分析结果显示,获得性TTP患者于首次缓解期内复发的独立危险因素包括ADAMTS13活性显著降低(OR=2.95,95％ CI:1.13～6.96,P＜0.05),检出抗ADAMTS13抗体(OR=3.31,95％CI:1.08～8.19,P＜0.05),检出抗ADAMTS13抑制物(OR=3.24,95 ％CI:1.24～9.03,P＜0.05).结论 获得性TTP患者在首次缓解期内,ADAMTS13活性水平显著降低,存在抗ADAMTS13抗体及抗ADAMTS13抑制物,会显著增加疾病复发风险,可以考虑将其作为预测获得性TTP患者于首次缓解期内复发的重要指标.     

以新单克隆抗体为基础的酶免疫测定法检测血浆ADAMTS 13活性浓度

背景ADAMTS13能特异性裂解大的血管假性血友病因子（VWF）多聚体，后者在高切应力下能诱发血小板性血栓形成。伴有血栓性血小板减少性紫癜（TTP）的病人ADAMTS 13活性低下。测定血浆中ADAMTS 13活性浓度是鉴别诊断血栓形成性微血管病的前提。本文介绍一种独特的高灵敏度的测定ADAMTS 13活性的酶免疫分析法（EIA）。研究设计与方法ADAMTS 13水解VWF中Y1605和M1606之间的肽键。     

在治疗的血浆制品中ADAMTS13活性的比较和稳定性

背景：血栓性血小板减少性紫癜（TTP）的患者通常缺乏血管性假血友病因子（VWF）裂解酶-ADAMTS13。TTP的基本治疗是血浆置换疗法（TPE），利用多种血浆制品帮助恢复ADAMTS13活性。然而，有多种置换制品可供选择。解冻的血浆制品具有依据产物类型的可变致冷保存期；保存在1C～6C的解冻制品中ADAMTS13的稳定性尚未被确定。     

Novel ADAMTS13 mutations in an obstetric patient with Upshaw‐Schulman syndrome

Upshaw‐Schulman syndrome (USS) is a rarely reported congenital form of thrombotic thrombocytopenic purpura (TTP) that results from mutations in the ADAMTS13 gene. Many USS patients are diagnosed during the second or third trimester of their first pregnancy. We present a patient diagnosed with USS following retinal detachments and intrauterine fetal demise at 34 weeks of gestation. The patient's plasma was tested for ADAMTS13 activity, inhibitor, and antibody. Subsequently, she and her first‐degree relatives had ADAMTS13 gene sequencing. Initially, the patient was found to have an ADAMTS13 activity of <5% in the absence of an ADAMTS13 inhibitor (FRETS assay) or antibody (immunoassay). Repeat studies in the months following hospital discharge showed persistent, undetectable ADAMTS13 activity and she was given a clinical diagnosis of USS. Molecular sequencing demonstrated two novel missense mutations in the ADAMTS13 gene: one in the maternal exon 17 (p.Ala690Thr due to nucleotide substitution c.2068 G>A) and another in the paternal exon 22 (p.Arg915Cys due to nucleotide substitution c.2746 C>T). In addition to being compound heterozygous for two ADAMTS13 mutations, the patient also had two maternally inherited single nucleotide polymorphisms: p.P618A (exon 16) and p.A732V (exon 18). Her parents and only sister had normal or near‐normal ADAMTS13 activity. Each was heterozygous for one of the novel missense mutations. This case highlights the importance of molecular analysis of the ADAMTS13 gene in patients and family members when the severe ADAMTS13 deficiency does not appear to be autoimmune in nature. J. Clin. Apheresis 28:311–316, 2013. © 2013 Wiley Periodicals, Inc.     

家族性高胆固醇血症患者二例的LDLR基因复合杂合新突变分析

目的 探讨2例临床确诊的湖北籍FH患者的LDLR基因突变状况,为FH的基因诊断提供依据.方法 收集2例临床确诊的FH患者及其父母血脂检测指标等临床资料,通过PCR扩增LDLR基因的1～18个外显子和内含子区域,再将扩增产物进行正、反双向核苷酸序列分析,并与GenBank中LDLR基因的正常序列对比找出突变后,结合FH先证者的临床表型证实致病突变的类型.结果 氧化酶法测定1号、2号FH先证者血浆TC,分别为12.79、11.98 mmol/L;经核苷酸序列分析,其ApoB100基因涵盖的3 500～3 531区域均未见突变;LDLR基因均为复合杂合突变,1号FH先证者LDLR基因第4外显子的665位碱基G>T为杂合错义突变,且该突变为新的点突变,第9内含子的1 358+32位碱基C>T突变也为新的点突变,并均由其父母遗传.2号先证者第9外显子1 257位碱基C>A突变导致终止密码子提前出现,但其核苷酸改变与比利时报道的C>G不同,第13外显子检测到1 879位碱基G>A杂合错义突变,且分别来源于其父母.结论 2例FH先证者均存在LDLR基因复合杂合突变,1号FH先证者的第4外显子665位碱基G>T和第9内含子1 358+32位碱基C>T、2号FH先证者的第9外显子1 257位碱基C>A突变均为新突变,这可能是导致FH的分子机制.

Abstract：

Objective To determine LDLR gene mutation in 2 clinically diagnosed FH patients from Hubei province and provide basis for gene diagnosis of FH.Methods Clinical data of 2 FH patients and their parents were collected.The promoter region and exon 1 to exon 18 region of LDLR gene were amplified through PCR and the amplified products were analyzed by forward and reverse DNA sequencing.The mutations were identified after comparison with LDLR gene sequence in GenBank.The pathogenic gene mutations were confirmed according to both genotype and phenotype of FH probands.Results The levels of plasma TC of two probands were 12.79 and 11.98 mmol/L.respectively.No gene mutations were detected in region 3 500 to 3 531 of ApoB100. The mutations of LDLR gene were compound heterozygous mutations. The novel mutation 665G > T detected in the exon 4 of No. 1 proband's LDLR gene was heterozygous missense mutation. The novel mutation 1 358 +32C > T was detected in the exon 9 of No. 1 proband's LDLR gene.The mutations 665G > T ( paternal origin) and 1 358 + 32C > T ( maternal origin) were inherited from the parents. A novel mutation 1 257 C > A was detected in the exon 9 of No. 2 proband's LDLR gene, resulting the presence of a premature termination codon, which was different from 1 257 C > G reported in Belgium.Another heterozygous missense mutation 1 879 G > A was detected in exon 13. They were derived from paternal origin and maternal origin, respectively. Conclusions There are three novel gene mutations:665G >T, 1 358 +32C > T, 1 257C > A found in two probands with compound heterozygous mutations in LDLR respectively. They maybe play a potential role in FH pathogensis.     

新的双重杂合性FV基因突变导致的重型遗传性FV缺陷症

目的对一个遗传性凝血因子V(FV)缺陷症家系进行FV基因突变的检测。方法用活化部分凝血活酶时间(Am)，凝血酶原时间(PT)及FV促凝活性(FV：C)和FV抗原(FV：Ag)测定进行表型诊断；用PCR法对先证者FV基因25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。突变位点经限制性内切酶分析证实：结果先证者APTT 249．2s．PT46．6s。TT17．9s，Fg3．42g/L，FV：C0．1％，FV：Ag 1．5％，FⅡ：C99％，FⅦ：C110％、FⅧ：C95％、FⅨ：C88％、FX：C120％、vWF121％；FV外显子区共发现4个与基因文库Z99572序列不同的位点，其中位于exon13区的杂合性2238～2239de1AG导致移码突变和终止密码子的提前m现(Asp689stop)，位于exon23区的杂合性G6410T错义突变导致Gly2079 Val.家系分析表明前者遗传于母亲，后者遗传于父亲。结论2238～2239delAG导致的移码突变和G6410T导致的错义突变．是导致先证者FV缺陷的原因。这是2个导致遗传性FV缺陷症的新的FV基冈突变位点。     

Ten candidate ADAMTS13 mutations in six French families with congenital thrombotic thrombocytopenic purpura (Upshaw–Schulman syndrome)

Summary.  ADAMTS13, the specific von Willebrand factor (VWF)-cleaving metalloprotease, prevents the spontaneous formation of platelet thrombi in the microcirculation by degrading the highly adhesive ultralarge VWF multimers into smaller forms. ADAMTS13 severe enzymatic deficiency and mutations have been described in the congenital thrombotic thrombocytopenic purpura (TTP or Upshaw–Schulman syndrome), a rare and severe disease related to multivisceral microvascular thrombosis. We investigated six French families with congenital TTP for ADAMTS13 enzymatic activity and gene mutations. Six probands with congenital TTP and their family were tested for ADAMTS13 activity in plasma using a two-site immunoradiometric assay and for ADAMTS13 gene mutations using polymerase chain reaction and sequencing. ADAMTS13 activity was severely deficient (< 5%) in the six probands and one mildly symptomatic sibling but normal (> 50%) in all the parents and the asymptomatic siblings. Ten novel candidate ADAMTS13 mutations were identified in all families, showing either a compound heterozygous or a homozygous status in all probands plus the previous sibling and a heterozygous status in the parents. The mutations were spread all over the gene, involving the metalloprotease domain (I79M, S203P, R268P), the disintegrin domain (29 bp deletion in intron/exon 8), the cystein-rich domain (acceptor splice exon 12, R507Q), the spacer domain (A596V), the 3rd TSP1 repeat (C758R), the 5th TSP1 repeat (C908S) and the 8th TSP1 repeat (R1096stop). This study emphasizes the role of ADAMTS13 mutations in the pathogenesis of congenital TTP and suggests that several structural domains of this metalloprotease are involved in both its biogenesis and its substrate recognition process.     

Congenital and acquired ADAMTS13 deficiency: Two mechanisms,one patient

Thrombotic thrombocytopenic purpura (TTP) is a life‐threatening microangiopathy with a heterogeneous and largely unpredictable course. It is caused by ADAMTS13 deficiency, that can be either congenital or due to anti‐ADAMTS13 autoantibodies development. ADAMTS13 deficiency is necessary but not always sufficient to cause acute clinical manifestations and trigger factors may be needed. We report the case of a woman diagnosed with congenital TTP in her adulthood, presenting with anti‐ADAMTS13 autoantibodies in acute phase during ticlopidine consumption. Noteworthy, the two ADAMTS13 mutations identified in this patient are novel: one is a splice‐site mutation located in intron 11 (c.1308+2_5delTAGG) and the other is a point missense mutation in exon 29 (c.4184T>C leading to p.Leu1395Pro substitution). Since congenital TTP is an extremely rare disease and drug‐induced TTP is an uncommon side effect of treatment with ticlopidine, the simultaneous occurrence of both mechanisms of disease in one patient is exceptional. This case represents TTP as a multifactorial disease, with ADAMTS13 genetic abnormality and environmental exposures acting together in determining individual clinical phenotype. J. Clin. Apheresis 30:252–256, 2015. © 2014 Wiley Periodicals, Inc.     

1例植物固醇血症的家系调查及致病基因突变研究

目的探讨1例植物固醇血症家系及其致病基因突变。方法对1例诊断为植物固醇血症的患者及其家系成员进行家系调查;通过PCR扩增先证者及其家系成员基因组DNA中ABCG5及ABCG8基因的所有外显子及其侧翼序列,采用Sanger测序法对PCR产物进行基因测序;采用Polyphen2及Mutation Taster生物信息学软件预测突变的致病性。结果 Sanger测序法发现先症者及家系成员中存在多个基因突变,其中ABCG5基因发现3个突变,分别为外显子1 c.64CT(p.Q22X)杂合无义突变、外显子10 c.1336CT(p.R446X)杂合无义突变、外显子13 c.1810CG(p.Q604E)杂合错义突变;ABCG8基因发现4个突变,分别为(ATG前)-19TG纯合突变、外显子2 c.161AG(p.Y54C)纯合错义突变、外显子13 c.1895TC(p.V632A)纯合错义突变、外显子4和5间的内含子g.12902TC纯合突变。Polyphen2及Mutation Taster软件预测ABCG5基因中c.64CT及c.1336CT为致病突变,其他基因突变均为非致病性的多态性位点。结论 ABCG5基因c.64CT及c.1336CT复杂杂合突变是该植物固醇血症家系的基因发病机制。     

A phenotype–genotype correlation of ADAMTS13 mutations in congenital thrombotic thrombocytopenic purpura patients treated in the United Kingdom

Summary. Background: ADAMTS13 mutations play a role in thrombotic thrombocytopenic purpura (TTP) pathogenesis. Objectives: To establish a phenotype–genotype correlation in a cohort of congenital TTP patients. Patients/Methods: Clinical history and ADAMTS13 activity, antigen and anti‐ADAMTS13 antibody assays were used to diagnose congenital TTP, and DNA sequencing and in vitro expression were performed to identify the functional effects of the ADAMTS13 mutations responsible. Results: Seventeen (11 novel) ADAMTS13 mutations were identified in 17 congenital TTP patients. All had severely reduced ADAMTS13 activity and antigen levels at presentation. Six patients with pregnancy‐associated TTP and six patients with childhood TTP were homozygous or compound heterozygous for ADAMTS13 mutations located in the metalloprotease (MP), cysteine‐rich, spacer and/or distal thrombospondin type 1 domains. The adults had TTP precipitated by pregnancy, and had overall higher antigen levels (median, 30 ng mL^?1; range, < 10–57 ng mL^?1) than the children (median, 14 ng mL^?1; range, < 10–40 ng mL^?1). Presentation in the neonatal period was associated with more intensive treatment requirements. The two neonates with the most severe phenotype had mutations in the first thrombospondin type 1 motif of ADAMTS13 (p.R398C, p.R409W, and p.Q436H). Using transfected HEK293T cells, we have shown that p.R398C and p.R409W block ADAMTS13 secretion, whereas p.Q436H allows secretion at reduced levels. Conclusions: This study confirms the heterogeneity of ADAMTS13 defects and an association between ADAMTS13 genotypes and TTP phenotype.     

山东地区甲状腺异位的先天性甲状腺功能减退症患儿TSHR基因突变研究

目的：对山东地区由甲状腺异位导致的先天性甲状腺功能减退症（CH）患儿 TSHR 基因第10外显子进行突变筛查,阐明山东地区CH患者TSHR基因突变类型和特点。方法以89例甲状腺异位导致CH的患儿为研究对象,采集外周血提取DNA,PCR扩增第10外显子,采用直接测序的方法对TSHR基因进行突变筛查。结果在89例研究对象第10外显子测序结果中,发现1个错义突变 c.1269G＞A （p.V424I）,1个SNP位点（rs1991517,c.2181G＞C,变异频率18.5%）。对小鼠、大鼠、猫、猪、牛、斑马鱼和人的TSHR蛋白进行同源性比较,结果表明第424密码子编码的氨基酸位于TSHR的保守区,该位点的缬氨酸被异亮氨酸取代（p.V424I）。结论山东地区甲状腺异位导致CH的患者中,TSHR基因第10外显子突变率较低。     

一个遗传性凝血因子ⅩⅢ缺陷症家系新的基因异常

目的对1例遗传性凝血因子Ⅻ（FⅫ）缺陷症家系进行基因分析，探讨其发病的分子机制。方法用尿素溶解法和Berichrom kit检测患者及其家系成员血浆FⅫ的活性．用火箭电泳和酶联免疫吸附试验测定FⅫ抗原含量。PCR法扩增FⅫA基因的所有外显子和侧翼序列．DNA测序分析基因异常，用直接测序法和限制性内切酶（SfaNⅠ、NspⅠ）分析80名正常人相应序列的PCR产物以排除基因多态性。应用生物信息学软件对所鉴定的突变进行分子模建，探讨其致病的分子机制。结果患者纤维蛋白凝块在5mol／L尿素中30min内完全溶解，加入正常人血浆后则24h不溶解，患者血浆FⅫ活性为0，FⅫA抗原含量〈2％，FⅫB抗原含量在正常范围。家系成员中其父母和外祖母血浆FⅫ活性和FⅫA抗原约为正常人一半。在患者FⅫA基因外显子15中发现两处杂合异常，分别位于177246位碱基（C→T，导：致Arg703→Trp）和177286位碱摹（A→G，导致His716→Arg），直接测序和酶切分析两种方法均排除了基因多态性。患者的母亲与外祖母为Arg703→Trp杂合子，患者的父亲为His716→Arg杂合子．分子模建分析表明，Arg703和His716两个位点突变后均可导致barrel2与core结构域之间距离和结合能力的政变，使蛋白质发生错误折叠，稳定性降低。His716→Arg还可能影响酶的催化活性基因的空间结构形成。结论FⅫA基因外显子15上Arg703→Trp、His716→Arg复合杂合突变影响了蛋白质的正确折叠和稳定性，造成患者FⅫ抗原和活性的缺失。此复合杂合错义突变是一种未报道过的新的突变类型。     

淋巴细胞恶性肿瘤p16基因纯合缺失和突变的研究

为了探讨非霍奇金淋巴瘤(NHL)和急性淋巴细胞白血病(ALL)中p16基因纯合缺失和突变情况,应用聚合酶链反应(PCR)技术与DNA单链构象多态性分析(PCR-SSCP)及DNA测序技术,检测了45例NHL及20例ALL p16基因改变情况。结果发现45例NHL中有4例存在p16基因纯合缺失,占8.9％,20例ALL中有5例存在p16基因纯合缺失,占25％。1例NHL在第2外显子上游第49密码子出现错义突变,由GCC突变为GAC。1例ALL在第2外显子上游65密码子出现错义突变,由GCC改变为GCA。研究结果表明,NHL和ALL中存在一定比例的p16基因纯合缺失,而p16基因突变率较低,提示p16基因纯合缺失在NHL和ALL发生发展中起一定作用。