This is the first patient who met the diagnostic criteria for systemic lupus erythematosus by the Systemic Lupus International Collaborating Clinics (SLICC) group. In addition to low T cells and low Treg cells, our study further revealed T cells and B cells activation enhanced in CD3γ deficiency patient, which may play an important role in autoimmunity. We believe that our study makes a significant contribution to the literature and will provide further insight into CD3γ deficiency and monogenic lupus.