Heredity in upper urinary tract urothelial carcinoma particularly relates to the Lynch syndrome, which is caused by germline mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2. The highest risks apply to colorectal cancer (50–80% lifetime risk) and endometrial cancer (40–60% lifetime risk), but efficient surveillance and prophylactic risk reduction procedures have led to improved survival rates and prolonged life expectancy. The gene discussed is MLH1; the disease is Lynch syndrome.