Lynch syndrome (hereditary non-polyposis colorectal cancer, HNPCC), is also an autosomal dominant tumor predisposition caused by germline mutations in DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6 or PMS2 with a life-time risk for colorectal cancer (CRC) of up to 80% and considerably increased risk of developing a broad spectrum of extracolonic malignancies including, among others, endometrial cancer (EC), stomach cancer and ovarian cancer[3,4]. Here, MLH1 is linked to hereditary nonpolyposis colon cancer.