Because the frequency of dead cells was equivalent between the two groups (Figure 3F, Supplementary Figures S7C, F) and because the in vitro assay demonstrated that CARS2 deficiency had no effect on T cell activation and differentiation (Supplementary Figures S8A, B), these results suggest that augmented accumulation of cytokine-secreting Cars2+/- CD4+ T cells in the colon may reflect an enhanced rate of lymphopenia-induced homeostatic proliferation. The gene discussed is CD4; the disease is lymphopenia.