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
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摘要
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.1366A>G突变(p.K456E),该家系成员中6名女性表型正常,检出c.1366A>G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。
Objective:To determine the BTK gene mutation types in a family with X-linked agammaglobulinemia(XLA),and to explored the genes diagnosis and treatment of XLA.Methods:The information of 21 family members including 1 sibling suspected XLA was assembled(including 1 patients died,and 2 fetuses).Eighteen peripheral blood samples and two fetal amniotic fluids were collected for DNA extraction.The 19 exons of BTK gene were amplified by PCR,and the products were directly sequenced.Results:A missense mutation of BTK gene in exon 15,c.1366 A>G(p.K456 E),was detected in the proband.All of the 6 female carriers in the family were detected to have carried this mutation.The patients died of XLA,because his mother was carriers.Two female carriers were detected DNA of amniotic fluid during pregnancy,respectively.The two male fetus were not detected the mutation and phenotype normal after birth.Conclusion:The clinicians need to master the situation of XLA patients.Consider disease diagnosis of genetic testing and using immunoglobulin replacement therapy as soon as possible.The parents can choose the prenatal diagnosis or pre-implantation genetic diagnosis to prevent the XLA patient was born.
Objective:To determine the BTK gene mutation types in a family with X-linked agammaglobulinemia(XLA),and to explored the genes diagnosis and treatment of XLA.Methods:The information of 21 family members including 1 sibling suspected XLA was assembled(including 1 patients died,and 2 fetuses).Eighteen peripheral blood samples and two fetal amniotic fluids were collected for DNA extraction.The 19 exons of BTK gene were amplified by PCR,and the products were directly sequenced.Results:A missense mutation of BTK gene in exon 15,c.1366 A>G(p.K456 E),was detected in the proband.All of the 6 female carriers in the family were detected to have carried this mutation.The patients died of XLA,because his mother was carriers.Two female carriers were detected DNA of amniotic fluid during pregnancy,respectively.The two male fetus were not detected the mutation and phenotype normal after birth.Conclusion:The clinicians need to master the situation of XLA patients.Consider disease diagnosis of genetic testing and using immunoglobulin replacement therapy as soon as possible.The parents can choose the prenatal diagnosis or pre-implantation genetic diagnosis to prevent the XLA patient was born.
引文
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[3]Hoshino A,et al.X-linked agammaglobulinemia associated with B-precursor acute lymphoblastic leukemia[J].Journal of Clinical Immunology,2015,35:108-111.
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[7]Bayrakci B,et al.The efficacy of immunoglobulin replacement therapy in the long-term follow-up of the B-cell deficiencies(XLA,HIM,CVID)[J].The Turkish Journal of Pediatrics,2005,47:239-246.
[8]Liu Y ZG,Zhang B.Bruton′s Tyrosine Kinase:Structure and Functions,Expression and Mutations[J].Gene Technology,2013,2.
[9]张晓敏,李虹,李强,等.六例X连锁无丙种球蛋白血症患儿BTK基因突变检测及临床分析[J].中华医学遗传学杂志,2014,31:29-33.
[10]Conley ME,Howard V.Clinical findings leading to the diagnosis of X-linked agammaglobulinemia[J].The Journal of Pediatrics,2002,141:566-571..
[11]Lee PPW,Chen TX,Jiang LP.Clinical Characteristics and Genotype-phenotype Correlation in 62 Patients with X-linked Agammaglobulinemia[J].Journal of Clinical Immunology,2010,30:121-131.
[12]Reda SM,El-Ghoneimy DH,Afifi HM.Clinical predictors of primary immunodeficiency diseases in children[J].Allergy,Asthma&Immunology Research,2013,5:88-95.
[2]Valiaho J,Smith CI,Vihinen M.BTKbase:the mutation database for X-linked agammaglobulinemia[J].Human Mutation,2006,27:1209-1217..
[3]Hoshino A,et al.X-linked agammaglobulinemia associated with B-precursor acute lymphoblastic leukemia[J].Journal of Clinical Immunology,2015,35:108-111.
[4]Tsukada S,et al.Deficient expression of a B cell cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia[J].Cell,1993,72:279-290.
[5]Mohamed AJ,et al.Bruton's tyrosine kinase(Btk):function,regulation,and transformation with special emphasis on the PH domain[J].Immunological Reviews,2009,228:58-73.
[6]Tzeng SR,et al.Stability and peptide binding specificity of Btk SH2domain:molecular basis for X-linked agammaglobulinemia[J].Protein science:a publication of the Protein Society,2000,9:2377-2385.
[7]Bayrakci B,et al.The efficacy of immunoglobulin replacement therapy in the long-term follow-up of the B-cell deficiencies(XLA,HIM,CVID)[J].The Turkish Journal of Pediatrics,2005,47:239-246.
[8]Liu Y ZG,Zhang B.Bruton′s Tyrosine Kinase:Structure and Functions,Expression and Mutations[J].Gene Technology,2013,2.
[9]张晓敏,李虹,李强,等.六例X连锁无丙种球蛋白血症患儿BTK基因突变检测及临床分析[J].中华医学遗传学杂志,2014,31:29-33.
[10]Conley ME,Howard V.Clinical findings leading to the diagnosis of X-linked agammaglobulinemia[J].The Journal of Pediatrics,2002,141:566-571..
[11]Lee PPW,Chen TX,Jiang LP.Clinical Characteristics and Genotype-phenotype Correlation in 62 Patients with X-linked Agammaglobulinemia[J].Journal of Clinical Immunology,2010,30:121-131.
[12]Reda SM,El-Ghoneimy DH,Afifi HM.Clinical predictors of primary immunodeficiency diseases in children[J].Allergy,Asthma&Immunology Research,2013,5:88-95.