In humans, HER-2 immunohistochemical expression varies according to tumour location, with a higher rate of HER-2 positivity in GEJ tumours compared to those located in the gastric body (34% vs 20%) [11].The single most important factor for the development of these tumours is the mucosal irritation caused by chronic GE reflux. The gene discussed is ERBB2; the disease is neoplasm.