Although eotaxin-3 was identified as the most highly expressed chemokine in esophageal biopsies from patients with EoE,1 serum eotaxin-3 has low sensitivity and specificity to diagnose or monitor EoE.1, 2, 3 Dellon et al.4 investigated the utility of serum biomarkers in EoE including IL-4, IL-5, IL-6, IL-9, IL-13, TGF-β, TNF-α, eotaxin -1, -2, -3, and thymic stromal lymphopoietin and found no difference in serum levels in EoE vs controls nor were they affected by therapy. This evidence concerns the gene IL9 and eosinophilic esophagitis.