GNAS and mucinous adenocarcinoma of the appendix: To date, studies have reported conflicting evidence on the prevalence of GNAS variants by tumor histological subtype among ACs.4,9,32 In a 2018 study of 703 AC samples,8GNAS variations were reported in 22% of nonmucinous adenocarcinomas and in 49% of mucinous adenocarcinomas of the appendix.