Deficiency in MMR enzymes has profound consequences on cellular health. It leads to a hypermutator phenotype, characterized by a high mutation rate, which can drive the development of cancer. For instance, hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is directly associated with inherited mutations in MMR genes. Furthermore, MMR deficiency is a hallmark of microsatellite instability (MSI), a condition observed in various types of tumors.
