PRB1 and mismatch repair cancer syndrome 1: Mismatch repair deficiency, defined by the loss of PMS and/or MSH6, was detected in 5/37 (13.5%) of gastric dysplasia and 1/36 (2.8%) of Barrett dysplasia; in 2/44 (4.5%) of LG dysplasia and in 4/29 (13.8%) of HG dysplasia; in 1/25 (4.0%) of LG gastric dysplasia, 4/13 (30.8%) of HG gastric dysplasia, 1/20 (5.0%) of LG Barrett dysplasia and was absent in HG Barrett dysplasia.