Novel deletion mutation in Bruton’s tyrosine kinase results in X-linked agammaglobulinemia:A case report  

作　　者：Xiao-Mei Hu Ke Yuan Hong Chen Chun Chen Yan-Lan Fang Jian-Fang Zhu Li Liang Chun-Lin Wang 

机构地区：[1]Department of Pediatrics,The First Affiliated Hospital of Zhejiang University,Hangzhou 310003,Zhejiang Province,China

出　　处：《World Journal of Clinical Cases》2020年第17期3859-3866,共8页世界临床病例杂志

基　　金：National Natural Science Foundation of China,No. 11571309;the Zhejiang Health Bureau Fund,No. 2016ZHA004。

摘　　要：BACKGROUND X-linked agammaglobulinemia is a primary immunodeficiency disease caused by gene mutations of Bruton’s tyrosine kinase(BTK).We found a new mutation point and summarized the correlation analysis and performed a literature review.CASE SUMMARY The proband was a 5-year-old boy.He was admitted to our hospital due to a recurrent cough and a fever that had persisted for a month.He had a history of multiple respiratory infections and sinusitis.There was no immunodeficiency or recurrent infection history among his family members.Agammaglobulinemia was characterized as follows:Immunoglobulin(Ig)A,90.0 mg/dL(90-450 mg/dL);IgG,20.0 mg/dL(800-1800 mg/dL);and IgM,18.0 mg/dL(60-280 mg/dL).Notably,the assessment of IgG subtypes revealed the following very low levels:Subtype 1,0.26 g/L(3.62-12.28 g/L);subtype 2,0.10 g/L(0.57-2.9 g/L);subtype 3,0.009 g/L(0.129-0.789 g/L);and subtype 4,0.003 g/L(0.013-1.446 g/L).Cellular immunological test results were as follows:CD3,74.6%(50%-84.0%);CD4,47.3%(27.0%-51.0%);and CD8,24.9%(15.0%-44.0%).A de novo hemizygous deletion in BTK was detected:c.902_c.904delAAG/p.E301del.Transcript levels of the mutant BTK were similar to those of the wild-type gene,though overexpression resulted in markedly reduced levels of mutant BTK(9.49%±1.58%),relative to the wildtype BTK(75.8%±2.98%,P<0.01).CONCLUSION This case of X-linked agammaglobulinemia was attributed to a de novo hemizygous deletion mutation in BTK(c.902_c.904delAAG/p.E301del).The mutation resulted in markedly reduced BTK protein stability in vitro.

关 键 词：AGAMMAGLOBULINEMIA Bruton’s tyrosine kinase MUTATION IMMUNODEFICIENCY Case report 

分 类 号：R593.31[医药卫生—内科学]