中国X连锁无丙种球蛋白血症40例基因型表型相关性分析

目的 通过中国X连锁无丙种球蛋白血症（XLA）患儿临床表现、免疫功能评价、Bruton′s 酪氨酸激酶（BTK）的表达及BTK基因突变分析,分析基因型和表型间可能存在的关系。 方法 选取拟诊为XLA患儿,使用抗BTK单克隆抗体通过流式细胞技术分析单核细胞BTK蛋白表达。采用RT-PCR获得患儿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。并对确诊XLA患儿的母亲及家族中部分亲属进行BTK蛋白表达和BTK基因分析。 结果 ①40/50例原发性低丙种球蛋白血症患儿经BTK基因突变分析确诊为XLA,以错义突变（16例,40.0%）和无义突变（13例,32.5%)为主。②突变类型为错义突变的患儿平均起病年龄为（1.4±1.1）岁,其他突变类型患儿为（1.4±0.7）岁,差异无统计学意义（P=0.45）。错义突变的发生率随年龄的增长呈上升趋势,无义突变的发生率呈下降趋势。③34/40例（85.0%）B细胞<0.1%;4例（10.0%）B细胞在1%~2%,其中错义突变2例,无义突变1例, 剪接突变1例;2例（5.0%）B细胞为2%,均为错义突变。④血清IgG<3 g·L-1患儿BTK基因突变类型以错义突变和无义突变为主。⑤错义突变患儿BTK蛋白表达水平与其他突变类型无显著差异。⑥6/21例（28.6%）2031C/T多态性患儿伴有严重的关节炎,3/19例（15.8％）无多态性患儿有关节炎表现。⑦28/32例（87.5%）XLA患儿母亲为BTK基因杂合型。 结论 错义突变可能与确诊年龄较大有关,且某些位点的错义突变可能与较高的外周血B细胞数量和血清IgG水平及正常的BTK蛋白表达水平有关。BTK基因多态性（2031C/T）可能增加关节炎的风险。     

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。     

儿童特发性肺动脉高压 ALK1 基因突变分析

目的探讨活化素受体样激酶1(ALK1)基因、骨形成蛋白Ⅱ型受体(BMPR2)基因突变与儿童特发性肺动脉高压(IPAH)之间的关系。方法收集14例临床诊断为IPAH患儿及其部分家族成员的DNA样本,对ALK1、BMPR2基因启动子及外显子区域进行二代测序,测序结果与GenBank人ALK1、BMPR2基因序列进行分析比对,对存在突变的基因进行一代测序验证。另收集106例健康儿童作为对照组。结果 1例女性IPAH患儿ALK1基因外显子3发生错义突变(c.77 CT:p.P 26 L);经数据库HMGD查对为一新突变位点。在1例女性患儿BMPR2基因外显子11发现错义突变(c.1447TC:p.C483R),1例男性患儿母亲BMPR2基因外显子5 splicing区域发现错义突变(c.621+8TC),1例女性患儿母亲BMPR2基因外显子10发现错义突变(c.1322GA:p.G441E),以上突变在既往文献中均已有报道。结论在我国汉族IPAH患儿中首次发现ALK1基因外显子3错义突变,该新错义突变可能和IPAH形成有关。     

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。     

Menkes病2家系临床和基因诊断研究

目的 对2个临床诊断为Menkes病的家系进行ATP7A基因突变筛查.方法 采用盐析法从2个家庭6个成员的外周血中提取基因组DNA.PCR扩增先证者及其父母ATP7A基因的编码外显子及两侧的侧翼内含子,直接测序分析.同时对先证者及健康对照者头发进行光镜检查.结果 PCR产物测序结果 显示,1号先证者ATP7A基因的第14外显子上发现核苷酸序列第3 045位碱基T缺失(c.3 045 del T).患儿母亲是这一缺失突变的杂合携带者,具有正常表型.2号先证者第14外显子核苷酸第2 956位碱基存在c.2 956 C>T的错义突变.先证者母亲不携带这个突变.2个先证者的父亲均具有正常基因型和表型.先证者头发光镜检查示头发较细、中空、颜色明显变浅.结论 ATPTA基因上c.3 045 del T碱基缺失突变是1号先证者的致病原因,患儿母亲是杂合携带者,该患儿为家族遗传性;c.2 956 C>T错义突变是2号先证者的致病原因,患儿母亲不是该突变的携带者,说明该患儿不是家族遗传性.     

7例原发性免疫缺陷病的临床及基因突变分析

探讨原发性免疫缺陷病的临床特点及其致病基因突变特点。7例患儿均为男性,年龄5个月至4岁6个月,均有反复呼吸道感染、肺炎病史,免疫球蛋白IgG及IgM水平低下,淋巴细胞亚群的绝对值或比例异常。高通量测序发现病例1的BTK基因存在c.1684C > T突变,病例2的BTK基因存在IVS8+2T > C剪接位点突变,两个突变均遗传自患儿母亲。病例3~5存在IL2RG基因突变,分别为c.298C > T、IVS3-2A > G以及c.164T > A突变,其中c.164T > A突变未见报道。病例6的RAG2基因存在c.204C > G突变,病例7的RAG2基因存在c.913C > T以及c.824G > A复杂杂合突变,分别遗传自父母。原发性免疫缺陷病患者存在免疫学指标异常,高通量测序有助于确诊。     

两种新型Wiskott-Aldrich综合征蛋白基因突变的鉴定

目的 明确3例Wiskott-Aldrich综合征(WAS)患儿WAS蛋白(WASP)基因突变的类型。方法 根据典型临床表现(血小板减少、湿疹、反复感染),及淋巴细胞和血小板扫描电镜改变,采用PCR直接测序法,对3例疑为WAS的患儿及其母亲的WASP基因进行序列分析。结果 以正义、反义引物扩增的PCR产物分别测序,发现两种新型WASP基因突变：2例WAS孪生兄弟WASP基因第10外显子,第984位核苷酸C缺失突变(984delC),导致317位密码子后移码突变,于444位密码子提前出现终止密码(H317fsX444);其母亲为此突变WASP基因携带者。另l例WAS患儿WASP基因第ll外显子,第1388位核苷酸由G替换为T(1388G→T),为无义突变,使第452位密码子提前变为终止密码(E452X)。其母亲无此突变WASP基因。结论 鉴定出两种新型WASP基因突变,WASP基因序列分析对于不典型和散发WAS的诊断及WASP突变基因携带者的检出有重要作用。     

丙酮酸激酶缺乏症2 家系基因变异分析

目的探讨丙酮酸激酶缺乏症(PKD)的临床及遗传学特点。方法回顾分析2例PKD患儿的临床资料,复习相关文献总结PKD的临床及遗传学特点。结果 2例患儿均为女孩,年龄3岁8个月和3岁10个月;均表现为巩膜黄染,中度贫血(血红蛋白60 g/L)。全外显子测序分析发现,例1的PKLR基因存在c.106GT以及c.817CT复合杂合突变,其中c.106GT突变遗传自父亲,而c.817CT遗传自母亲,患儿姑姑为c.106GT突变携带者;例2 PKLR基因存在c.1279GT以及IVS6-1GT复合杂合突变,其中c.1279GT突变遗传自母亲,IVS6-1GT突变遗传自父亲。例1的复合杂合突变未影响患者PKLR基因表达,而例2剪接位点IVS6-1GT突变可能影响PKLR基因的RNA水平。结论两个PKD家系均为PKLR基因变异,基因检测有助PKD诊断。     

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。     

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。     

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.     

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。     

Early and prolonged intravenous immunoglobulin replacement therapy in childhood agammaglobulinemia: a retrospective survey of 31 patients

OBJECTIVE: To evaluate the outcome of children who received prolonged intravenous immunoglobulin (IVIg) replacement therapy early in life for X-linked agammaglobulinemia (XLA). STUDY DESIGN: We performed a retrospective study of the clinical features and outcome of patients with genetic and/or immunologic results consistent with XLA. Patients receiving IVIg replacement therapy within 3 months of the diagnosis and for at least 4 years between 1982 and 1997 were included. RESULTS: Thirty-one patients began receiving IVIg replacement therapy at a median age of 24 months and were followed up for a median time of 123 months. IVIg was given at doses >0.25 g/kg every 3 weeks, and mean individual residual IgG levels ranged from 500 to 1140 mg/dL (median, 700 mg/dL). During IVIg replacement, the incidence of bacterial infections requiring hospitalization fell from 0.40 to 0.06 per patient per year (P <. 001). However, viral or unidentified infections still developed, including enteroviral meningoencephalitis (n = 3) causing death in one patient, exudative enteropathy (n = 3), and aseptic arthritis (n = 1). At last follow-up, 30 patients were alive at a median age of 144 months (range, 58 to 253 months). Among 23 patients who were evaluated by respiratory function tests and computed tomography, 3 had an obstructive syndrome, 6 had bronchiectasis, and 20 had chronic sinusitis. CONCLUSION: Early IVIg replacement therapy achieving residual IgG levels >500 mg/dL is effective in preventing severe acute bacterial infections and pulmonary insufficiency. More intensive therapy may be required to fully prevent the onset of bronchiectasis, chronic sinusitis, and nonbacterial infections, particularly enteroviral infections, in all cases.     

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.     

Treosulfan‐based reduced toxicity hematopoietic stem cell transplantation in X‐linked agammaglobulinemia: A cost‐effective alternative to long‐term immunoglobulin replacement in developing countries

X‐linked agammaglobulinemia (XLA) is a primary antibody disorder due to a mutation in the Bruton tyrosine kinase gene that requires lifelong immunoglobulin replacement resulting in a significant economic burden and treatment abandonment. Hematopoietic stem cell transplantation (HSCT) offers an alternative option for complete cure. In our series, two children with XLA underwent successful HSCT using a myeloablative conditioning with thiotepa, treosulfan, and fludarabine from a matched sibling donor. The second child had rejected his first graft following a busulfan‐based regimen with resultant autologous reconstitution. At 6 months post‐HSCT, serum IgG were normal, off IVIG, and had no infections. Both children after a median follow‐up of 20 months have 100% chimerism. Treosulfan‐based reduced toxicity myeloablative HSCT has encouraging results with a positive impact on the socioeconomics in developing countries.