MSH2 and neoplasm: Among the 69 patients with an MSH2 abnormality, we noted that three (4.3%) exhibited rare cytoplasmic MSH2 localization in tumor cells but showed patchy expression of the MSH6 protein that was somewhat weaker in tumor cells than in internal control cells (patient 164 and patient 271 from one family pedigree and patient 345) (Figures 1 and S2).