Abstract: To investigate the clinical and immunological characteristics of a child with atypical severe combined immunodeficiency caused by RAG1 mutation by analyzing the clinical data，TREC/KRECs content，refined immune typingand TCR Vβ subfamily clonal patterns of the child， who was admitted to Children’s Hospital of Chongqing Medical University on July 3，2020. This was an 8-month-old girl who presented with AIHA and ITP as first symptoms，accompanied by fever and diarrhea. Immunological analysis revealed a T-B+NK- phenotype，and TREC/KREC content was significantly lower than normal.The TCR Vβ subfamilies mostly showed monoclonal peaks.After steroid pulse therapy，intravenous immunoglobulin，eltrombopag and mycophenolate mofetil，there was no obvious effect.While waiting for transplantation，the patient died of intracerebral hemorrhage due to intractable thrombocytopenia.The clinical manifestations of immune deficiency disorders caused by RAG1/RAG2 gene mutation are various，especially when autoimmune hemocytopenia is the first symptom，which makes it very likely to have missed or delayed diagnosis; moreover，the treatment effect is not good.Early identification and diagnosis and timely stem cell transplantation may reduce mortality.

Key words: recombinantion activating gene, atypical severe combined immunodeficiency, cytopenia, autoimmune, hematopoietic stem cell transplantation

摘要： 分析重庆医科大学附属儿童医院风湿免疫科于2020-07-03收治的1例RAG1突变患儿临床资料、TRECs/KRECs、精细免疫分型、TCR Vβ亚家族克隆谱型等，以探讨RAG1突变致不典型重症联合免疫缺陷病的临床与免疫学特征。结果显示，患儿女，8月龄，以自身免疫性溶血性贫血、原发性血小板减少为首发表现，伴发热、腹泻症状；患儿淋巴细胞分类为T－B＋NK－表型；TREC、KREC含量均明显低于健康同龄儿童；TCR Vβ亚家族多表现为单克隆峰。予一线治疗（激素冲击、静脉应用丙种球蛋白）、二线治疗（艾曲波帕、吗替麦考酚酯）效果不理想，在等待移植过程中，因顽固性血小板降低致颅内出血死亡。RAG1/RAG2基因突变所致免疫缺陷病临床表现多样，特别是以自身免疫性血细胞减少为首发症状时，容易存在漏诊或延迟诊断现象，且治疗效果不理想。早期识别并诊断，尽早进行干细胞移植可能降低病死率。

关键词: 重组激活基因, 不典型重症联合免疫缺陷, 血细胞减少症, 自身免疫, 造血干细胞移植