X-连锁无丙种球蛋白血症患儿临床表型和基因诊断分析

目的分析3例X-连锁无丙种球蛋白血症(X-linked agammaglobulinemia,XLA)的临床表型特点及Bruton’s酪氨酸激酶(BTK)基因变异情况,以提高临床医师对XLA的认识。方法收集本组3例XLA患儿外周静脉血,测定其血清Ig水平和淋巴细胞亚群表达情况,采用RT-PCR和测序的方法分析患儿及母亲BTK基因变异情况,并总结其临床特征。结果在临床特征方面3例均为男性患儿,诊断XLA时的年龄分别为4岁、12岁6个月和2岁2个月,平均诊断年龄6岁3个月。3例患儿临床均表现为反复感染,如患中耳炎、鼻窦炎、反复全身脓疱疹、脓胸、细菌性关节炎、细菌性脑膜炎等,3例诊断时均表现为营养、生长发育较差,周围淋巴组织发育不良,扁桃体和淋巴结很小或难以查及;实验室检查血清Ig和循环B淋巴细胞明显降低;在基因诊断方面3例均发现存在BTK基因突变,例1为外显子9的949位G缺失,例2为外显子17的错义突变,例3为外显子15的错义突变,对例2、例3患儿母亲进行BTK基因分析,发现均为携带者,存在相同的基因突变。结论本组3例中国贵州籍XLA患儿诊断时年龄较大,临床主要表现为不同部位的反复化脓性细菌感染,在临床表现基础上通过BTK基因分析有助于XLA患儿的进一步明确诊断,并且有利于发现携带者和进行遗传咨询。     

X-连锁无丙种球蛋白血症临床分析及基因诊断

目的分析X-连锁无丙种球蛋白血症(XLA)的临床特点及Bruton酪氨酸激酶(BTK)的基因突变情况。方法回顾分析通过基因检测确诊的20例XLA患儿的临床资料,以及采用Sanger测序方法分析BTK基因的突变情况。结果 20例患儿均为男性,发病年龄6～54月龄,平均(26.3±14.61)月龄;基因诊断确诊年龄26～168月龄,平均(64.7±38.22)月龄;诊断周期中位数为27.5月龄(3～114月龄)。临床表现以呼吸道感染为主,其中18例诊断为肺炎,另外2例为消化道感染。免疫功能检测示成熟B淋巴细胞缺如或比例显著降低,血清IgG、IgA及IgM水平明显降低。基因检测提示错义突变10例,无义突变4例,移码突变3例,内含子剪切位点突变2例,剪接突变1例。20例患儿明确诊断后均给予静脉输注丙种球蛋白替代治疗,感染频次均显著减少,均无后遗症。结论对反复严重、特殊部位感染的男童,尤其是有相关家族史的患儿,尽早行免疫功能筛查,并行基因检测明确诊断及遗传咨询。     

X连锁无丙种球蛋白血症的基因诊断

目的研究我国X连锁无丙种球蛋白血症(XLA)患者Bruton’s酪氨酸激酶(BTK)基因的突变类型。方法采用逆转录-聚合酶链反应(RT—PCR),获得7例XLA患者cDNA。使用8对不同引物分2步扩增BTK cDNA,PCR产物测序。突变结果通过对DNA外显子相应部位扩增、测序证实。对其中4例母亲进行基因分析。结果7例患者的基因突变均位于BTK基因的编码区,3例在BTK的血小板-白细胞C激酶底物同源区,2例位于酪氨酸激酶区,其他2例分别位于Src同源区2和Src同源区3。突变包括：错义突变、无义突变、重复序列和片段缺失。除错义突变引起单一BTK氨基酸改变外,突变还分别造成终止密码子形成和阅读框架移位。其中4例为未见报道的新突变。进行基因分析的4例母亲中,3例为携带者。结论本组患者临床表现为典型XLA,检测出的7种突变均位于BTK基因编码区,其中4种是未见报道的新突变。XLA可以通过基因分析进行确诊以区别与其他低丙种球蛋白血症。     

X-连锁无丙种球蛋白血症3例报告并文献复习

目的分析X-连锁无丙种球蛋白血症(XLA)的临床表现、诊断和治疗特点。方法回顾性分析3例XLA患儿的临床特点、细胞免疫、体液免疫指标及治疗和预后。结果 3例XLA患儿的发病年龄自11个月至6岁,中位诊断年龄为12岁。患儿均表现为多发反复细菌感染;关节炎症累及膝、踝、肘和髋等大关节。实验室检查提示血清免疫球蛋白水平及循环B细胞明显降低。3例患儿均发现存在BTK基因突变,分别为外显子3的移码突变及无义突变,外显子10的移码突变,以及外显子18的错义突变。确诊为XLA后予静脉滴注丙种球蛋白(IVIG)替代治疗;合并关节炎加用非甾体类抗炎药物(NSAIDs),酌情加用小剂量激素,病情得到明显改善。结论 XLA临床表现具有较大的变异性,反复不同部位的细菌感染,扁桃体、淋巴结发育不良及血清免疫球蛋白水平低下是早期诊断XLA的重要环节;XLA合并关节炎使用IVIG和NSAIDs联合治疗,谨慎使用激素或免疫抑制剂。     

X连锁无丙种球蛋白血症的临床特点及基因检测

目的探讨X连锁无丙种球蛋白血症(XLA)的临床特点及检测其致病基因BTK的临床意义。方法回顾性分析1例X连锁无丙种球蛋白血症的临床表现、实验室检查及基因检测的特点,同时复习XLA的流行病学及发病机制等相关文献,尤其是有关XLA基因检测的研究。结果 1例XLA患儿反复感染,表现为肺炎、急性支气管肺炎并伴有感音神经性耳聋。实验室检查,超敏C反应蛋白升高(103 mg/L),各种免疫球蛋白均下降,T淋巴细胞百分比升高,CD19+B淋巴细胞绝对值及百分比均为0。基因检测,BTK基因EXON7至EXON19缺失,下游基因TIMM8A也缺失。结论 XLA患者临床表现为反复感染,免疫球蛋白下降,外周血B细胞下降。检测BTK基因可帮助临床诊断。     

流式细胞技术在诊断X-连锁无丙种球蛋白血症的应用

目的：探讨流式细胞技术在诊断X-连锁无丙种球蛋白血症(XLA)中的应用。方法：采用流式细胞术检测白细胞分化抗原19(CD19),统计循环B细胞数量,从而使XLA的临床诊断更可靠。结果：8例IgG<2 g/L 的男性患儿中5例(62.5%)CD19<1%而确诊为XLA者。结论：应用流式细胞术检测CD19可提高诊断XLA的准确率。     

X连锁无丙种球蛋白血症的临床特点

目的 探讨中国X连锁无丙种球蛋白血症(XLA)的临床表现和实验室检查特点。方法 本组8例,经流式细胞仪检测Bruton′s酪氨酸激酶(BTK)表达和(或)基因分析诊断为XLA,总结其临床表现,并对其免疫功能进行评价。结果 本组8例,均为男性。发病年龄3个月～3岁,诊断为XLA时平均年龄6岁。8例患儿都有反复急性上呼吸道感染和肺炎伴发热,上呼吸道感染主要为鼻咽部感染,仅1例曾患中耳炎。反复多关节炎较多见(3/8),没有关节感染的证据。仅2例母系家族中的男性有类似疾病史。诊断时均表现为营养不良和生长发育延迟。周围淋巴组织发育不良,扁桃体和淋巴结很小或难以查及。实验室检查血清Ig和循环B细胞明显降低。6例CIM/CD8比值明显倒置。结论 本组中国XLA患儿诊断时年龄较大,临床表现以反复呼吸道感染、肺炎为主,多关节炎发生率较高,家族史不明显。大部分患儿存在CD4/CD8比值明显倒置,原因和意义尚不清楚。     

性联无丙种球蛋白血症的Btk蛋白表达的研究

通过对8例性联低丙球血症（XLA）患儿Btk蛋白表达的研究。了解Btk蛋白表达缺陷与XLA的相关性。应用蛋白印迹技术，观察患儿及对照组儿童Btk蛋白表达条带分布情况，结果发现正常儿Btk蛋白表达正常，而XLA者则有Btk蛋白表达缺陷。提示测定Btk蛋白表达情况对XLA的诊断有重要意义。     

17例X连锁无丙种球蛋白血症临床表型分析

目的：分析17例单中心临床诊断的X连锁无丙种球蛋白血症（X-linked agammaglobulinemia, XLA）的临床表型特点。方法：2000年1月至2007年4月北京儿童医院住院患儿,根据临床反复感染表现、血IgG<2g/L、外周血成熟B淋巴细胞缺失或明显降低（<1%）诊断为XLA者,分析临床特点,总结规律。结果：首次诊断年龄平均为7.7岁,88.2%患儿首次诊断年龄>6岁。首次出现症状年龄平均为4.2岁,11.8%患儿首次出现症状年龄<1岁,17.6%患儿首次出现症状年龄为1~2岁。64.7%患儿首发症状为呼吸系统感染,大部分患儿均以此为主诉入院。35.3%患儿有关节炎表现。皮肤及软组织感染少见于<1岁年龄组。大年龄组患儿可出现突发败血症和/或深位部感染。结论：该组患儿发病年龄及首次诊断年龄均较迟,呼吸系统感染为最常见的主诉,关节炎的比例较高。>1/2的患儿血CD4+T细胞减少,CD8+T细胞增加,CD4/CD8比例倒置,NK细胞减少。     

8例非Bruton酪氨酸激酶基因突变无丙种球蛋白血症患儿临床特征和基因突变/多态性分析

目的分析8例非Bruton酪氨酸激酶(BTK)基因突变无丙种球蛋白血症患儿的临床特征和基因突变/多态性特点。方法以2005年1月至2010年12月于上海交通大学医学院附属上海儿童医学中心诊断为无丙种球蛋白血症但BTK基因未检测出突变的患儿为研究对象,分析其临床资料和实验室结果。Sanger法检测其常见致病基因,包括IGHM、IGLL1、CD79a和CD79b。结果共纳入8例患儿,男女比例为3:1,平均发病年龄(3.7±2.4)岁。所有患儿均有反复感染史,其中最为常见的是肺炎和上呼吸道感染。1例患儿检测出IGLL1基因突变,其他致病基因未明。结论非BTK基因突变无丙种球蛋白血症患儿常见呼吸系统感染,可通过基因分析进行确诊。     

Mutation screening of the BTK gene in 56 families with X-linked agammaglobulinemia (XLA): 47 unique mutations without correlation to clinical course

OBJECTIVES: To determine the utility of single-stranded conformation polymorphism (SSCP) analysis for mutation screening in the BTK (Bruton's tyrosine kinase) gene, we investigated 56 X-linked agammaglobulinemia (XLA) families. To obtain genotype/ phenotype correlations, predicted protein aberrations were correlated with the clinical course of the disease. PATIENTS: This study included 56 patients with XLA, with or without a positive family history, who were diagnosed on the basis of their clinical features, low peripheral B-cell count, and low immunoglobulin levels. Ten patients with isolated hypogammaglobulinemia and 50 healthy males served as controls. METHODS: SSCP analysis was performed for the entire BTK gene, including the exon-intron boundaries and the promoter region. Structural implications of the missense mutations were investigated by molecular modeling, and the functional consequences of some mutations also were evaluated by in vitro kinase assays and Western blot analysis. RESULTS: We report the largest series of patients with XLA to date. All but 5 of the 56 index patients with XLA screened with SSCP analysis showed BTK gene abnormalities, and in 2 of the 5 SSCP-negative patients, no BTK protein was found by Western blot analysis. There were 51 mutations, including 37 novel ones, distributed across the entire gene. This report contains the first promoter mutation as well as 14 novel missense mutations with the first ones described for the Tec homology domain and the glycine-rich motif in the SH1 domain. Each index patient had a different mutation, except for four mutations, each in two unrelated individuals. This result supports the strong tendency for private mutations in this disease. No mutations were found in the controls. CONCLUSIONS: Our results demonstrate that molecular genetic testing by SSCP analysis provides an accurate tool for the definitive diagnosis of XLA and the discrimination of borderline cases, such as certain hypogammaglobulinemia or common variable immunodeficiency patients with overlapping clinical features. Genotype/ phenotype correlations are not currently possible, making prediction of the clinical course based on molecular genetic data infeasible.     

3例低血磷性抗维生素D佝偻病的基因诊断及文献复习

对3例临床疑似X连锁低血磷抗维生素D佝偻病（XLH）患儿进行磷酸盐调节基因（PHEX）分析并确诊的临床资料进行回顾性分析及相关文献复习,探讨中国人存在的突变热点和突变类型。3例患儿均检测到PHEX基因突变,1例为无义突变（c.58C>T）,2例为剪接突变（c.1645+1G>A,c.436+1G>A）,其中c.436+1G>A为新突变。至2014年1月,世界上已报道的PHEX基因突变共有329个,错义突变占数量最多（24%）,突变热点区域有3个。不同地区的病例总数和突变类型存在差异。中国人群中,89例XLH病人进行了PHEX基因检测,发现28种突变,其中在22外显子上发现的突变数量最多（18%）,突变类型最多的为错义突变（61%）。总之,在中国人群中,XLH病人PHEX基因最常见的突变位置为第22外显子,最常见的突变类型为错义突变;c.436+1G>A 为PHEX基因的新突变。     

Clinical features and mutation analysis of X-linked agammaglobulinemia in 20 Chinese patients

Background

X-linked agammagobulinemia (XLA) is a primary immunodeficiency caused by Bruton’s tyrosine kinase (BTK) gene mutation. XLA patients have an extremely small amount of peripheral B cells and profound deficiency in all immunoglobulin isotypes. We analyzed the clinical, immunologic, and molecular characteristics of children with XLA in an attempt to improve the diagnosis and treatment of XLA in China.

Methods

Twenty children with XLA-compatible phenotypes from 18 unrelated families were enrolled in this study. The BTK gene was amplified and sequenced, followed by mutation analysis in these children and their female relatives.

Results

Eighteen different mutations of the BTK gene were identified in the 20 patients. Eleven mutations had been reported previously including eight missense mutations (c.994C>T, c.1987C>A, c.1885G>T, c.502T>C, c.1085C>T, c.1816C>T, c.214C>T, c.1912G>A) and three nonsense mutations (c.1267T>A, c.1793C>G, c.1618C>T). Seven novel mutations of the BTK gene were also presented and included five missense mutations (c.134T>A, c.1646T>A, c.1829C>G, c.711G>T, c.1235G>A), one splice-site mutation (c.523+1G>A) and one insertion mutation (c.1024-1025in sTTGCTAAAGCAACTGCTAAAGCAAG). Eight out of 18 mutations of the BTK gene were located in the TK domain, 4 in the PH domain, 4 in the SH2 domain and 2 in the TH domain. Genetic study for carrier status was carried out in 18 families with definite BTK gene mutations. Nine carriers with BTK gene mutations were identified. Six families without carriers were detected, and 3 patients were not tested in this study.

Conclusion

Our results support that molecular genetic testing represents an important tool for early confirmed diagnosis of congenital agammaglobulinemia and may allow accurate carrier detection and prenatal diagnosis.     

Genotype-phenotype correlation in Bruton's tyrosine kinase deficiency

Bruton's tyrosine kinase (Btk) belongs to the Tec family of nonreceptor protein tyrosine kinases. Mutations in the BTK gene cause X-linked agammaglobulinemia (XLA); a primary immunodeficiency disorder in human. No clear genotype-phenotype correlation has been established in XLA so far. To determine how differently mutations in BTK affect the severity of the disease and if BTK promoter polymorphic variant or intron 1 polymorphic variant in Tec, a cytoplasmic tyrosine kinase that might substitute for Btk, could contribute to the clinical phenotype, we analyzed the clinical and molecular findings in a cohort of XLA patients. Polymorphisms in BTK promoter and TEC intron 1 regions include substitutions of C>T (rs2071219) and T>C (rs2664019), respectively. Btk expression was evaluated by means of western immunoblotting and fluorescence-activated cell sorter analysis. Mutations were categorized as mild or severe and patients were evaluated for the clinical severity of disease. On the basis of the results, severe genotypes do not necessarily lead to severe phenotypes. More over, in a considerable number of patients with mild phenotype we showed a severe mutation with a tendency toward C substitution in the polymorphic site on TEC intron 1.     

X-连锁低磷性佝偻病的基因突变分析

目的：研究X-连锁低磷性佝偻病（XLH）患儿致病基因的突变频率和突变类型,探讨存在突变热点的可能性及基因型与临床表型的关系。方法：回顾性分析10例XLH患儿的临床资料,评估其基因突变类型及其与疾病严重程度之间的关系。结果：10例XLH患儿均检测到PHEX基因突变,其中6例为错义突变,2例为拼接位点突变,1例为框移突变,1例为无义突变。还发现了两个新突变,即c.2048T>C 和IVS14+1delAG。PHEX基因的突变类型与矮小程度、腿弯程度之间没有关联（分别P=0.571、0.467）;基因的突变位置与矮小程度、腿弯程度之间也没有关联（分别P=0.400、1.000）。结论：错义突变是XLH患儿最常见的突变类型;c.2048T>C 和IVS14+1delAG是PHEX基因的两个新突变。PHEX基因的突变类型和突变位置与疾病的严重程度无相关性。     

Composition of precursor B-cell compartment in bone marrow from patients with X-linked agammaglobulinemia compared with healthy children.

X-linked agammaglobulinemia (XLA) is characterized by a severe B-cell deficiency, resulting from a differentiation arrest in the bone marrow (BM). Because XLA is clinically and immunologically heterogeneous, we investigated whether the B-cell differentiation arrest in BM of XLA patients is heterogeneous as well. First, we analyzed BM samples from 19 healthy children by flow cytometry. This resulted in a normal B-cell differentiation model with eight consecutive stages. Subsequently, we analyzed BM samples from nine XLA patients. Eight patients had amino acid substitutions in the Bruton's tyrosine kinase (BTK) domain or premature stop codons, resulting in the absence of functional BTK proteins. In seven of these eight patients a major differentiation arrest was observed at the transition between cytoplasmic Ig(mu-) pre-B-I cells and cytoplasmic Ig(mu+) pre-B-II cells, consistent with a role for BTK in pre-B-cell receptor signaling. However, one patient exhibited a very early arrest at the transition between pro-B cells and pre-B-I cells, which could not be explained by a different nature of the BTK mutation. We conclude that the absence of functional BTK proteins generally leads to an almost complete arrest of B-cell development at the pre-B-I to pre-B-II transition. The ninth XLA patient had a splice site mutation associated with the presence of low levels of wild-type BTK mRNA. His BM showed an almost normal composition of the precursor B-cell compartment, suggesting that low levels of BTK can rescue the pre-B-cell receptor signaling defect, but do not lead to sufficient numbers of mature B lymphocytes in the peripheral blood.     

VEGF-A基因在汉族先天性房室间隔缺损患儿中的突变分析

目的分析血管内皮生长因子（VEGF）-A基因在汉族先天性房室间隔缺损（AVSD）患儿中的突变情况。方法收集119例汉族AVSD患儿（包括合并21-三体综合征10例）临床资料和基因组DNA,PCR扩增VEGF-A的全部外显子编码序列及两侧部分非编码序列,用荧光素末端标记法经全自动遗传分析仪进行自动测序、Blast比对进行突变筛查和分析,并以100名年龄匹配的健康汉族人群作为对照。结果在119例患儿中发现1例插入突变（插入序列为22₂3GACA）,1例错义突变（碱基变化A962G,氨基酸变化为K321R）,23例无意义碱基突变,其中19例位于外显子1上,4例位于外显子3上。结论 VEGF-A基因与人类心内膜垫和房室瓣发育有关,VEGF-A基因突变与先天性房室间隔缺损具有相关性;VEGF-A在AVSD患儿中基因突变的检出率低,提示AVSD可能是多基因遗传。