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中国循证儿科杂志

中国循证儿科杂志 ›› 2012, Vol. 7 ›› Issue (1): 4-10.

• 论著 • 上一篇    下一篇

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

王晓川   

  1. 复旦大学附属儿科医院儿科研究所
  • 收稿日期:2011-12-12 修回日期:2012-01-04 出版日期:2012-01-10 发布日期:2012-03-15
  • 通讯作者: 王晓川

Characterization and correlation of genotype with phenotype of 40 cases of X-linked agammaglobulinemia in China

  • Received:2011-12-12 Revised:2012-01-04 Online:2012-01-10 Published:2012-03-15

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摘要： 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。

关键词: Bruton′s tyrosine kinase, Bruton′s酪氨酸激酶, Flowcytometry, Genotype, Mutation analysis, Phenotype, Primary agammaglobulinemia, X-linked agammaglobulinemia, X连锁无丙种球蛋白血症, 表型, 基因分型, 基因型, 流式细胞仪, 原发性低丙种球蛋白血症

Abstract: Objective To explore the phenotype-genotype correlation of X-linked agammaglobulinemia（XLA） between clinical and immunological phenotypes and gene cDNA mutaions. Methods Using anti-BTK monoclone antibody the expression level of BTK protein was measured by flowcytometry. The BTK mutations in XLA patients were detected using PCR and direct sequencing. Some of the patients′ mother and relatives were also taken BTK mutation analysis. Results ①Forty of 50 XLA patients were identified to have BTK gene mutation.The major types of BTK mutation were missense(16 cases) and nonsense mutations(13 cases).②The age of onset of the XLA patients with missense mutations and other mutation were (1.4±1.1) and （1.4±0.7）years（P=0.45). The proportion of missense mutation increased, whereas the proportion of nonsense mutation decreased with the age of onset increasing. ③The numbers of circulating B cells of 34 cases(85%) were below 0.1%; 4 cases were between 1% and 2%. Among these 4 patients, two cases were missense mutation, one case was nonsense mutation and one case was splice-site mutation. Two cases with 2% B cells carried all missense mutiation. ④The major types of BTK mutation of the patients with low levels of serum IgG(<3 g·L-1) were missense mutation and nonsense mutation. ⑤There was no significant difference in exppression level of BTK protein between the patients with missense mutation and patients with other mutation types. ⑥6 of 21 cases with 2031 polymorphism had severe arthritis.Among 19 cases without 2031 polymorphism,3 cases had recurrent arthritis. ⑦28 of 32 mothers (87.5%) were confirmed to be carriers of BTK mutation. Conclusions There was no clear genotype-phenotype correlation in Chinese XLA patients. Missense and nonsense mtation were the most common types of mutation in Chinese XLA patients. Missense mutation may be related to relatively high levels of IgG and expression level of BTK protein. Polymorphic variant (2031T>C) in exon 18 may partly contribute to the clinical phenotype of arthritis.