The loss of mucosal glands in atrophic gastritis is replaced with a growth of new immature glandular and epithelial elements; that is, with glands of intestinal type (“intestinal metaplasia (IM)”), resembling glands and epithelium in colon and/or small bowel, and/or with pyloric type (“pseudopyloric metaplasia”), resembling pyloric glands and epithelium from which the G cell (gastrin cell) are disappeared. This evidence concerns the gene GAST and chronic atrophic gastritis.