Two families with gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS): case reports and literature review.

Background: Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), a hereditary gastric polyposis syndrome that presents with fundic gastric polyposis, is associated with an increased risk of gastric adenocarcinoma. The four patterns of point mutation in the () promoter 1B region have been identified as the cause of GAPPS. GAPPS was first reported in 2012, and only 33 families with GAPPS have been reported worldwide to date. Therefore, the clinical management for GAPPS are still controversial. We herein report two unrelated GAPPS families with the same point mutation site.

Case Description: Total seven patients of two families had >100 carpeting polyps in the gastric body and fundus, and one of them (69-year-old female) had gastric adenocarcinoma. As a result of germline analysis, both families harbored a point mutation (c.-192A>G) in promoter 1B region, previously reported in only one family. Three of seven patients underwent total gastrectomy, and others were followed-up with regular esophagogastroduodenoscopy (EGD) and biopsy every 6 months. To summarize the reported cases, total 42 patients of 35 families have developed gastric adenocarcinoma.

Conclusions: This report may contribute to determining the appropriate guidelines for the clinical practice of GAPPS. When EGD reveals gastric polyposis localized to the gastric body and fundus, it is important to obtain a detailed family history and perform germline mutational analysis. And more, point mutation type of our family cases was a rare pattern, suggested that c.-192A>G pattern might be a pathogenic variant.