TCF3 and systemic lupus erythematosus: However, its existence in humans has been highly controversial because of the scarcity of well-characterised examples.13, 14, 15 In this report, superimposition of a de novo Transcription Factor 3 (TCF3) mutation in a family already carrying a C104R (c.310T>C) mutation of the TACI gene causes a severe CVID-like disorder and systemic lupus erythematosus (SLE) in the proband.