In EoE, PPAR-γ-positive CD4± T cells were recently identified (Wen et al., 2019) and a study (Nhu et al., 2020) demonstrated a higher expression of PPAR-γ mRNA in EoE-derived fibroblasts, upregulated by IL-4 stimulation, and that expression of PPAR-γ was detectable in the epithelium and subepithelial lamina propria of active EoE but not in the normal esophagus. The gene discussed is CD4; the disease is eosinophilic esophagitis.