Loss-of-function variants in CTNNA1 detected on multigene panel testing in individuals with gastric or breast cancer

CTNNA1 LOF variants are detected on MGPT with a majority of these individuals having gastric or breast cancer. The overall risk of gastric cancer for CTNNA1 LOF carriers may be lower than expected. Given the uncertain phenotype and penetrance, management of individuals with CTNNA1 LOF variants remains challenging.