Mutation screening of the BTK gene in 56 families with X-linked agammaglobulinemia (XLA):: 47 unique mutations without correlation to clinical course
Mutation screening of the BTK gene in 56 families with X-linked agammaglobulinemia (XLA):: 47 unique mutations without correlation to clinical course
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DOI：
10.1542/peds.101.2.276
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发表时间：
1998-02-01
期刊：
影响因子：
8
通讯作者：
Meindl, A
中科院分区：
文献类型：
--
作者：
Holinski-Feder, E;Weiss, M;Meindl, A
目标.为了确定单链构象多态性（SSCP）分析在BTK（布鲁顿酪氨酸激酶）基因突变筛查中的实用性，我们调查了56个X连锁无丙种球蛋白血症（XLA）家族。为了获得基因型/表型相关性，预测的蛋白质畸变与疾病的临床过程相关。这项研究包括56名XLA患者，有或没有阳性家族史，他们根据临床特征，外周血B细胞计数低和免疫球蛋白水平低进行诊断。10例单纯性低丙种球蛋白血症患者和50例健康男性作为对照。对整个BTK基因进行SSCP分析，包括外显子-内含子边界和启动子区。通过分子模拟研究了错义突变的结构意义，并通过体外激酶试验和Western blot分析评估了部分突变的功能后果。我们报告了迄今为止最大的XLA患者系列。SSCP分析显示，56例XLA患者中除5例外，其余均显示BTK基因异常，5例SSCP阴性患者中有2例Western blot分析未发现BTK蛋白。有51个突变，包括37个新的，分布在整个基因。该报告包含第一个启动子突变以及14个新的错义突变，其中第一个描述了Tec同源结构域和SH 1结构域中富含甘氨酸的基序。每个索引患者有不同的突变，除了四个突变，每个在两个无关的个体。这一结果支持了这种疾病中私人突变的强烈趋势。对照组中未发现突变。我们的研究结果表明，通过SSCP分析的分子遗传学检测为XLA的明确诊断和边缘病例的鉴别提供了准确的工具，例如某些低丙种球蛋白血症或具有重叠临床特征的常见可变免疫缺陷患者。基因型/表型相关性目前是不可能的，使得基于分子遗传数据的临床过程的预测是不可行的。
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.