More than 1,000 constitutional gene variants in MLH1, MSH2, MSH6 and PMS2 have been classified as pathogenic or likely pathogenic in patients affected by Lynch syndrome [52], an autosomal dominant condition also known as hereditary non-polyposis colorectal cancer (HNPCC) and characterized by increased susceptibility to colorectal (25%–70%), endometrial (30%–70%), and other types of cancer [53]. Here, MLH1 is linked to hereditary nonpolyposis colon cancer.