They found that Gpr15 expression was increased in highly polarized pathogenic effector Th2 (peTh2) clonotypes detected in both esophageal tissue and peripheral blood of patients with EoE, and Gpr15 was the most significantly upregulated transcript in these cells in the esophagus compared with peripheral blood. The gene discussed is GPR15; the disease is eosinophilic esophagitis.