Increased age was positively associated with tumour MMR deficiency (OR 1.02, 95% CI 1.00–1.04, p = 0.013), MSI-H (OR 1.03, 95% CI 1.01–1.05, p = 0.003), and MLH1-hypermethylation (OR 1.04, 95% CI 1.02–1.06, p < 0.001) (tumours in which methylation testing was not indicated were assumed to have normal MLH1 methylation), whilst negatively associated with LS (0.95, 95% CI 0.92–0.99, p = 0.006). This evidence concerns the gene MLH1 and mismatch repair cancer syndrome 1.