The etiology of MMRd for 228 of these CRCs was known comprising 47 (20.6%) CRCs from people with Lynch syndrome, and 181 (79.4%) related to sporadic causes namely MLH1 promoter methylation (n = 108; 47.4%) and double somatic MMR mutations (n = 73; 32%). The gene discussed is MLH1; the disease is Lynch syndrome.