Referring to the studies on EoE, assessment using immunohistochemical markers, such as IgG4, eotaxin-3, cysteine-rich secretory protein 3, GATA binding protein 3, and periostin matrix metalloproteinases, can be useful in disease diagnosis and determination of appropriate treatments [33]. The gene discussed is GATA3; the disease is eosinophilic esophagitis.