目的　探讨白细胞介素-2受体共同γ链（IL2RG）基因突变所致重症联合免疫缺陷病的临床特征和基因突变 类型。方法　回顾分析1例IL2RG基因突变所致重症联合免疫缺陷病患儿的临床资料。结果　患儿，男，48天，生后早期 多重感染，白细胞减少，抗生素治疗效果差。患儿IgG 2.93 g/L，IgA＜0.07 g/L，lgM 0.16 g/L，C3 0.67 g/L，C4 0.13 g/L； CD3+CD4+ T淋巴细胞0.03%、CD3+CD8+ T淋巴细胞0.1%、CD3－/CD16+CD56+ NK细胞2.6%；CD3－CD19+ B淋巴细 胞96.76%。二代基因测序显示患儿IL2RG基因（HG19位置chrX：70328484）存在半合变异c.816_819delGATT（p.L273fs*20）， 为罕见移码突变。软件预测该突变导致蛋白质合成提前出现终止密码，为1类致病突变。患儿母亲为杂合状态，患儿父亲 无此突变，患儿姨妈也有该杂合突变。结论　发现1例由IL2RG基因 [c.816-819delGATT (p.L273fs*20)]突变所致的重症 联合免疫缺陷病患儿。基因测序分析结合性别鉴定可在先证者家系中筛查携带者及产前诊断。

Objective　To explore the clinical characteristics and gene mutation types of severe combined immunodeficiency (SCID) caused by gene mutation of interleukin-2 receptor common γ-chain (IL2RG). Method　The clinical data of SCID caused by IL2RG gene mutation in a child were retrospectively analyzed. Results　A 48-day-old male infant presented multiple infections, leukopenia and poor efficacy of antibiotics in the early postnatal period. The infant had IgG 2.93 g/L, IgA < 0.07 g/L, IgM 0.16 g/L, C3 0.67 g/L and C4 0.13 g/L, the proportion of CD3+CD4+ T lymphocytes at 0.03%, CD3+CD8+ T lymphocytes 0.1%, CD3－/CD16+CD56+ NK cells 2.6% and CD3－CD19+ B lymphocytes 96.76%. Secondgeneration gene sequencing showed that the IL2RG gene (chrX: 70328484, HG19) had a hemizygous variation of c.816_819 delGATT (p.L273fs*20), which was a rare frame shift mutation. The software predicted that the mutation would lead to an early termination codon in protein synthesis, which was a type-1 pathogenic mutation. The mother of the infant was in a heterozygous state, the father did not have this mutation, and the mother's sister also had this heterozygous mutation. Conclusion　We found a case of SCID caused by mutation of IL2RG gene [c.816-819delGATT (p.L273fs*20)]. Gene sequencing analysis combined with sex identification can screen carriers in proband families and make prenatal diagnosis.