GNAS1 mutation analysis in gastrointestinal tumors.

GNAS1 codes for a part of the a-stimulatory subunit (Gsa) of the G protein. Mutation of GNAS1 has been frequently found in myxoid soft tissues, however, in gastrointestinal tumors, little is known about the mutation status of GNAS1. The aim of the study was to analyze the occurrence of GNAS1 mutations indifferent gastrointestinal, gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and colorectal tumors. Mutation status of GNAS1 exon 8 was analyzed in one hundred thirty-five formalin-fixed, paraffin-embedded (FFPE) gastrointestinal tumor samples including 45 tubular-villous adenomas, 11 tubular adenomas, 6 villousadenomas, 10 hyperplastic gastric polyps, 31 GEP-NETs and 32 colorectal adenocarcinomas by using polymerase chain reaction (PCR) and direct sequencing. Five GNAS1 mutations were found in 2 tubular-villous adenomas, 2 villous adenomas and 1 colorectal adenocarcinoma. No mutations were detected in the tubular adenomas, the hyperplastic gastric polyps or GEP-NETs. GNAS1 mutation is not a frequent molecular event in GEP-NETs or hyperplastic gastric polyps. The study confirms the presence of GNAS1 mutations in colon tumors with villous differentiation.