Disease-causing mutations do not compromise proliferation of naive CD4⁺ T cells. Naive CD4⁺ T cells from healthy donors (solid gray histograms) and patients (overlay black histograms) with the indicated gene mutations were labeled with CFSE, and then cultured with TAE beads (Th0) for 5 d. After this time, the cells were harvested and analyzed for proliferation by assessing CFSE dilution. Histograms are representative of experiments performed using naive CD4⁺ T cells from nine different healthy controls, two patients with mutations in STAT3, STAT1, CD40LG, NEMO, BTK, IL12RB1, or IFNGR1, or individual patients with mutations in IL21R, IL10R, or ICOS.