原发性低丙种球蛋白血症Bruton′s酪氨酸激酶表达研究

目的　研究临床诊断为原发性低丙种球蛋白血症Bruton′s酪氨酸激酶 (BTK)表达及意义。方法　使用抗BTK单克隆抗体通过流式细胞仪技术分析细胞内BTK表达。经临床和常规实验室检查诊断为原发性低丙种球蛋白血症的 8例来自不同家系的患者和其中 5例患者的母亲。结果　正常对照者单核细胞BTK表达均大于 95 %。 8例受检患者中 7例单核细胞中BTK表达明显降低 ,基因分析存在BTK突变。 1例BTK表达正常 ,基因分析BTK正常。检测的 5例患者母亲中 3例单核细胞BTK表达降低 ,BTK基因分析也表现为嵌合型。 2例BTK表达正常 ,BTK基因正常。结论　通过流式细胞仪检测单核细胞内BTK表达可作为诊断X 连锁无丙种球蛋白血症 (XLA)手段之一 ,并可能用于甄别XLA携带者。     

原发性低丙种球蛋白血症Bruton''s酪氨酸激酶表达研究

目的 研究临床诊断为原发性低丙种球蛋白血症Bruton’s酪氨酸激酶(BTK)表达及意义。方法 使用抗BTK单克隆抗体通过流式细胞仪技术分析细胞内BTK表达。经临床和常规实验室检查诊断为原发性低丙种球蛋白血症的8例来自不同家系的患者和其中5例患者的母亲。结果 正常对照者单核细胞BTK表达均大于95％。8例受检患者中7例单核细胞中BTK表达明显降低，基因分析存在BTK突变。1例BTK表达正常，基因分析BTK正常。检测的5例患者母亲中3例单核细胞BTK表达降低，BTK基因分析也表现为嵌合型。2例BTK表达正常，BTK基因正常。结论 通过流式细胞仪检测单核细胞内BTK表达可作为诊断X-连锁无丙种球蛋白血症(XLA)手段之一，并可能用于甄别XLA携带者。     

X-连锁无丙种球蛋白血症研究现状与展望

X-连锁无丙种球蛋白血症(X-Linked Agammaglobulinemia,XLA)属于原发性体液免疫缺陷病，由于Btk基因突变导致B细胞发育障碍，所以不能产生免疫球蛋白。本文对BTK的遗传学特性、基因突变分析及分子致病机制进行综述。     

X-连锁无丙种球蛋白血症研究现状与展望

X-连锁无丙种球蛋白血症(X-Linked Agammaglobulinemia,XLA)属于原发性体液免疫缺陷病,由于Btk基因突变导致B细胞发育障碍,所以不能产生免疫球蛋白.本文对BTK的遗传学特性、基因突变分析及分子致病机制进行综述.     

BTK基因与X-染色体连锁无丙种球蛋白血症

BTK是一种细胞内的非受体型蛋白酪氨酸激酶 ,与多种细胞内的功能有关。已发现 BTK基因突变是引起 X染色体连锁无丙种球蛋白血症 ( XL A)的重要机制。本文将 BTK基因的发现、结构、编码蛋白以及 XL A患者发生的 BTK基因的突变类型作一综述     

一例X连锁先天性无丙种球蛋白血症家系报告及产前诊断

目的确定一个X连锁先天性无丙种球蛋白血症(X-linked agammaglobulinemia,XLA)家系BTK基因的突变类型,探讨对XLA的基因诊断及治疗。方法以1例临床拟诊断为XLA的兄妹及家系成员共21人为研究对象(包括1名患儿已死亡,以及2名胎儿),对18名家庭成员采集外周血样及2名胎儿分别于孕16+周进行产前诊断羊水穿刺,分别提取外周血DNA和羊水DNA。首先对先证者使用聚合酶链反应扩增BTK基因19个外显子与内含子连接区,PCR产物正反向测序并与BTK基因序列进行比对确定有无BTK基因突变,及突变位点及类型。针对所找到的突变位点,对其父母及其他家系成员进行DNA序列分析。结果在先证者的BTK基因第15外显子检测到c.1366AG突变(p.K456E),该家系成员中6名女性表型正常,检出c.1366AG杂合突变。其中1名死亡患儿的母亲为携带者;2名女性携带者孕期分别进行羊水核型分析,提示胎儿为男胎,进行羊水DNA检测,未检测到此位点突变,分娩出表型正常男婴。结论对于罕见的XLA病例,需要临床医生熟悉免疫缺陷相关的严重临床表现,考虑疾病诊断的基因检测,尽早使用免疫球蛋白替代治疗,以便达到一个较好的临床结局。产前诊断或者在孕前选择胚胎植入前的基因诊断,可以预防XLA患儿出生。     

X-连锁无丙种球蛋白血症合并血液肿瘤患儿的临床及免疫学特征分析

目的探讨X-连锁无丙种球蛋白血症(X-linked agammaglobulinaemia,XLA)合并血液肿瘤患儿的临床特征和免疫学特征,提高临床医生对XLA合并血液肿瘤的认识。方法回顾性分析我国首例XLA合并间变性大细胞淋巴瘤患儿的临床特征、实验室检查、免疫学特征及诊治经过;搜索国内外相关文献并加以分析。结果患儿表现为反复呼吸道感染、中耳炎、鼻窦炎,5岁并发间变性大细胞淋巴瘤。免疫学检查提示外周B细胞缺如,各型免疫球蛋白下降,基因分析发现Bruton酪氨酸激酶BTK基因c.1909-2AG剪接突变。查询国内外相关文献,国外已报道9例XLA患者并发血液肿瘤,包括白血病和淋巴瘤,国内尚无相关报道。结论该患儿为我国第1例XLA合并血液肿瘤患者,得到了及时诊疗。文献提示XLA仍有发生血液肿瘤的风险,临床医生应该警惕该合并症的发生。     

利用全外显子测序技术发现BTK基因新生突变

目的利用全外显子测序技术,对疑似X-连锁无丙种球蛋白血症患儿及父母进行测序,发现致病基因突变并明确临床诊断,探讨基因型与临床表型之间的关系及分子诊断的意义。方法提取疑似X-连锁无丙种球蛋白血症患儿及其父母外周血,应用全外显子组捕获高通量测序筛查患儿及父母基因组DNA。通过生物信息学分析,结合dbSNP、千人基因组、ExAC、gnomAD数据库分析变异频率,确定突变位点,用Sanger测序法进行验证。结果通过全外显子测序,在患儿BTK基因中找到一个新发错义杂合突变c.1781GA(p.G594E),该位点位于已报道的热点位置,其父母此位点为正常基因型。结合临床表型和基因检测结果,该患儿被确诊为X-连锁无丙种球蛋白血症。结论本研究明确了X-连锁无丙种球蛋白血症临床表型和该BTK突变位点的相关性。通过全外显子测序技术成功鉴定了BTK基因的突变,强调了该技术在儿童先天性免疫缺陷病的明确诊断和遗传咨询中的实用性     

Rett综合征MECP2基因突变分析

目的 分析我国典型的Rett综合征患儿甲基化CpG结合蛋白－2基因（methyl-CpG-binding protein 2,MECP2）突变。方法 使用PCR扩增、单链构象多态性分析、PCR产物克隆和DNA测序的方法。检测分析了26例Rett综合征患儿、其父母和其中2例患儿的妹妹MECP2基因3个外显子的基因突变。结果 26例Rett综合征患儿中发现14例有9种类型MECP2基因的杂合性突变，突变均位于第3外显子。其中7例有3种错义突变：C473T（T158M)4例,C674G(P225R)1例，C916T（R306C）2例；4例有3种无义突变：C502T（R168X）2例，C763T（R255X）1例，C880T（R294X）1例；2种由于缺失导致的突变：1例为1152del 44bp和1例1158－1167／1171－1186del 26bp；1鲍由于碱基插入导致的移码突变：874insA。1158－1167／1171－1186del 26bp和874insA突变为首次报千，突变均为新生突变。此外，新发现了一种源于你亲的错义变异1141G（P381A）。结论 我国Rett综合征患儿存在MECP2基因突变，典型的Rett综合征MECP2基因突变率大于50％。     

深圳地区苯丙酮尿症患儿苯丙氨酸羟化酶基因突变特征及分布情况研究

目的了解深圳地区苯丙酮尿症(phenylketonuria,PKU)患儿苯丙氨酸羟化酶(phenylalanine hydroxylase,PAH)基因突变特征及分布情况,为该地区PKU产前诊断、治疗及干预措施的制定提供科学依据。方法收集2013年2月~2017年9月在深圳市光明新区人民医院产科分娩的新生儿经深圳市新生儿遗传性疾病筛查中心确诊为PKU患儿27例,采用聚合酶链反应(PCR)直接测序法对PKU患者PAH基因突变型进行检测,并对检测结果进行统计分析。结果 27例PKU患儿中检出2个基因突变类型的16例,占59.26%(16/27),其中3例为纯合子突变,明显高于1个基因突变类型的37.04%(10/27)和1例未检出基因突变类型的3.70%(1/27),差异有统计学意义(χ2=3.105~9.683,P0.05);27例PKU患儿54个PAH等位基因中共检出44个基因突变位点,检出率为81.48%(44/54),且此44个突变基因中共检出14种基因突变类型,包括错义突变7个,无义突变3个,剪接突变1个,同义突变1个,缺失突变2个,其中以R243Q,Y356X和R241C突变检出率最高,分别为20.37%,14.81%和12.96%,明显高于其它基因突变类型,差异有统计学意义(χ2=3.921~11.518,P0.05)。结论深圳地区PKU患儿PAH基因突变检出率比较高,且基因突变类型呈现多样化和复杂化,但未检出新的PAH基因突变类型,以R243Q,Y356X和R241C突变类型检出率最高。     

Novel insertions of Bruton tyrosine kinase in patients with X-linked agammaglobulinemia

Mutations in the gene encoding Bruton tyrosine kinase (BTK) result in X-linked agammaglobulinemia (XLA), an immunodeficiency of antibody defect. By using base excision sequence scanning method (BESS) followed by direct sequencing we found in seven unrelated families with a classical XLA phenotype various mutations including six novel mutations (g.64512_64513insC, c.108_109insG, c.1700_1701insACTACAG, g.51375_51376GC>TG, g.63991_63992insGGTAGAAAAAA, c.1956_1957insCA) and a previously known silent polymorphism (c.2031C>T). Except for two mutations, the alterations affect the kinase domain. There was exceptionally high proportion of insertions in the cohort. Frameshift insertion was found altogether in five patients, three of which are on introns, one in upstream region, and one in exon 18 leading to frameshift mutation and truncation of the protein. In the intron 4 there is a substitution of two bases. Carrier detection was performed in four families. In one case the mutation was found to be de novo.     

Molecular analysis of Bruton’s tyrosine kinase gene in Spain

Mutations in Bruton’s tyrosine kinase (BTK) gene result in X linked agammaglobulinemia (XLA). Using Single Strand Conformation Polymorphism (SSCP) followed by direct sequencing 21 mutations were found in 27 patients with an XLA phenotype from 21 unrelated families. We identified 13 novel and 8 known mutations: seven missense (R288W, R544G, P566S, K430E; K374N, L512P, R544S), 5 nonsense (Q196X, Y361X, L249X, Q612X, Q466X), 2 deletions of one nucleotide (A207fsX216, Q612fsX648), 2 deletion‐insertions (V219fsX227, K218fsX228), one insertion of two nucleotides (S572fsX587) and 4 point mutations in donor/acceptor splice sites (g.IVS1+1G>C, g.IVS6+5G>A, g.IVS10+1G>T, g.IVS13‐1GG>CT). Carrier detection was performed in 18 mothers. Only in one case the mutation was found to be de novo. Additionally, BTK mutations were not found in four patients without family history, but with XLA‐compatible phenotype. Hum Mutat 18:84, 2001. © 2001 Wiley‐Liss, Inc.     

Delayed diagnosis in X-linked agammaglobulinemia and its relationship to the occurrence of mutations in BTK non-kinase domains

Background: X-linked agammaglobulinemia (XLA) is characterized by the absence of immunoglobulin and B cells. Patients suffer from recurrent bacterial infections from early childhood, and require lifelong immunoglobulin replacement therapy. Mutations in BTK (Bruton’s Tyrosine Kinase) are associated with this phenotype. Some patients that present XLA do not show typical clinical symptoms, resulting in delayed diagnosis due to the lack of a severe phenotype. This study presents a report of five XLA patients from four different families and attempts to determine a relationship between delayed diagnosis and the occurrence of BTK mutations.

Methods: Samples from patients with antibody deficiency were analyzed to determine BTK expression, immunophenotyping and mutation analysis. Clinical and laboratory data was analyzed and presented for each patient.

Results: Most patients presented here showed atypical clinical and laboratory data for XLA, including normal IgM, IgG, or IgA levels. Most patients expressed detectable BTK protein. Sequencing of BTK showed that these patients harbored missense mutations in the pleckstrin homology and Src-homology-2 domains. When it was compared to public databases, BTK sequencing exhibited a new change, along with three other previously reported changes.

Conclusions: Delayed diagnosis and atypical manifestations in XLA might be related to mutation type and BTK expression.     

Maternal germinal mosaicism of X‐linked agammaglobulinemia

X‐linked agammaglobulinemia (XLA) is an immunodeficiency caused by abnormalities in tyrosine kinase (BTK), and is characterized by a deficiency of peripheral blood B cells. We studied cytoplasmic expression of BTK protein and analyzed the BTK gene (BTK) in peripheral blood mononuclear cells from two siblings with XLA and additional family members. Cytoplasmic expression of BTK protein in monocytes was not detected in either patient with XLA. A single base deletion (C563) in BTK‐exon 6, which encodes the TH domain, was identified in both XLA patients. However, normal cytoplasmic expression of BTK protein in monocytes was detected in their mother without any BTK mutation. These results strongly suggest germinal mosaicism in the mother. © 2001 Wiley‐Liss. Inc.     

Characterization of germline mutations of the gene encoding Bruton's tyrosine kinase in families with X-linked agammaglobulinemia

Bruton's tyrosine kinase (Btk) has been identified as the protein responsible for the primary immunodeficiency X-linked agammaglobulinemia (XLA) and has been described as a new member of Srcrelated cytoplasmic protein tyrosine kinases. We have recently characterized the structure of the entire gene encoding Btk and developed a polymerase chain reaction (PCR)-based assay to detect germline mutations within it. In this report we describe six mutations, five of which are novel, of the Btk gene in patients with XLA and demonstrate the inheritance pattern of the defect within the families of the affected individuals. The mutations found include two nonsense and two missense mutations, a single base deletion at an intron acceptor splice site, and a 16-bp insertion. A single Strand conformation polymorphism was also found in the 5′ end of intron 8 with the same assay. This technique has provided a powerful tool for direct analysis of the Btk gene for the diagnosis of XLA and carrier detection. The identification of new mutations may eventually reveal the role of Btk in the signaling pathways involved in B-cell development. © 1995 Wiley-Liss, Inc.     

Mutation of the <Emphasis Type="Italic">BTK</Emphasis> Gene and Clinical Feature of X-Linked Agammaglobulinemia in Mainland China

Introduction  X-Linked agammaglobulinemia is a prototypical humoral immunodeficiency with the mutation of the Bruton’s tyrosine kinase gene. Methods  We investigated the gene mutation and clinical features of 30 Chinese X-linked agammaglobulinemia (XLA) patients from 27 families. There were 26 mutations, including 11 novel and 15 recurrent mutations, distributing over the entire gene. The nucleotide and amino acid aberration, 1129C>T(H333Y) and 1196T>A(I355N), in SH2 have not been reported before. Five (I355N, W124R, R520X, I590F, G594E) of the 24 mutations not detected in the mothers receiving gene analysis were determined to be de novo. Two mutations occurred within intronic splice-site sequences (intron5(−2)A>G, intron17(−2)A>T). Results and Discussion  There are eight mutations in the PH domain, two mutations in the SH3 domain, three mutations in the SH2 domain, one mutation in the TH domain, and other 16 mutations in the TK domain. The mutations of protein domain is most common in TK (53%) domain and then in PH(8%) domain. Missense and nonsense mutations were found equal in 46% of the detected mutations. All of the patients are alive, but one died of liver cancer. Clinical features and serum Igs levels range variedly and were not correlated with genotypes. Our results demonstrated molecular genetic characteristics of XLA in mainland China.     

BTK mutations in patients with X-linked agammaglobulinemia: lack of correlation between presence of peripheral B lymphocytes and specific mutations

X-linked agammaglobulinemia (XLA) is a human antibody deficiency that results from mutation of the tyrosine kinase btk. We tested the hypothesis that XLA patients who varied from the classic phenotype of XLA by presence of normal or near normal number of peripheral B lymphocytes would have a set of mutations of BTK that is different from the mutations found in patients without peripheral B lymphocytes. The mutations of BTK we found in two patients with normal numbers of peripheral B lymphocytes have been previously identified in patients without peripheral B lymphocytes. A third patient, without peripheral B cells, was found to express normal levels of wild type btk. Exmination of the mutations of the BTK gene in patients in the BTKbase who were identified as having peripheral B lymphocytes found that these same mutations, or mutations of the same protein domains, were also present in patients identified as lacking peripheral B lymphocytes. Analysis of mutations in BTK has previously led to the conclusion that severity of disease in XLA cannot be predicted from the specific mutation of BTK. The results of this study suggest that whether an XLA patient will develop peripheral B lymphocytes cannot be predicted from the specific mutation of BTK.     

DNA-based mutation analysis of Bruton's tyrosine kinase gene in patients with X-linked agammaglobulinaemia

The identification of the BTK (Bruton's tyrosine kinase) genedefective in human immunoglobulln deficiency X-linked agammaglobulinaemla(XLA) and characterlsation of BTK exon–intron boundarleshas now allowed the analysis of mutations and polymorphismsat the level of genomic DNA. Using Southern blot analysis andthe polymerase chain reaction single strand conformation polymorphism(PCR–SSCP) assay, amplifying all 19 exons and the putativepromoter region with a single annealling temperature, mutationshave been identified in 19 out of 24 unrelated patients diagnosedas having XLA. Apart from a large deletion involving exon 19,nine missense (F25S, R288W, I370M, M509V, R525P, N526K, R562W,A582V and G594R), two nonsense (E277X and R525X), five frameshiftand two splice site mutations have been found affecting mostcoding exons and all major enzyme domains. No mutations or polymorphismswere detected in the putative promoter region. A single nucleotidedeletion located in the last exon, resulting in a truncationof the eight C-terminal residues of Btk and a typical XLA phenotype,indicates structural and/or functional importance of Btk helixI In the catalytic domain. Although allelic heterogeneity atthe BTK locus may partly explain clinical variability In familleswith XLA, compensatory and redundant mechanisms involved inB-cell development must play a role in the phenotypic diversityof the disease.