Among the 20 cases displaying normal MMR protein expression by IHC, 2 cases (LCH-4 and LCH-12) displayed tumor MSI-H phenotype, one case (GDLG-18#III-19) carried a germline deletion of MSH2 exon 3 and 2 cases (311#2042 and LCH-15) carried missense MLH1 variants (c.731GA and c.1918CT, respectively) previously reported as potentially pathogenic based on functional or in silico analyses, respectively (Table 1) [41,42]. The gene discussed is MRC1; the disease is neoplasm.