Cimetidine, a histamine H2 receptor antagonist that reduces gastric acid secretion, is used in the management of peptic ulcer disease, dyspepsia and gastro-oesophageal reflux disease while Erythromycin is an anti-infective that inhibits bacterial protein synthesis and also acts as an immuno-modulatory and anti-inflammatory agent [49]. The gene discussed is HRH2; the disease is gastroesophageal reflux disease.