Consequently, LS-associated tumors commonly exhibit MMR deficiency (dMMR), as reflected by high-level microsatellite instability (MSI-H) or loss of MMR protein expression, which are the main features of these tumors [9,10], whereas few cases are caused by biallelic somatic MMR gene inactivation and are termed “Lynch-like syndrome” (LLS) [11]. The gene discussed is MRC1; the disease is mismatch repair cancer syndrome 1.