Expression levels of NHE3 mRNA in the esophagus of patients with Grade A or Grades B-D GERD were higher than the levels of the control subjects (Fig. 2D, P < 0.001), but the levels were similar between the patients with different grades of GERD (Fig. 2D, P > 0.05). The gene discussed is SLC9A3; the disease is gastroesophageal reflux disease.