Notably, if deficiencies in MMR (including defects in MLH1, PMS2, MSH2, and MSH6 [5, 6, 191, 192]) and DNA proofreading polymerases (POLE [193–196] and POLD1 [193]) are known to drive MSI, hypermutability, elevated TMB, and a resultant increased tumour antigenicity [197–199], deficiencies in other DDR pathways appear to be less effective in doing so [200]. Here, MLH1 is linked to neoplasm.