system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Patient with HNPCC (hereditary nonpolyposis colon cancer) has genes with microsatellite instability. This is due to failure of which repair mechanism of DNA
assistant
The correct answer is  Mismatch repair: It is one of the repair mechanisms in DNA replication. It operates when there is mismatched base paining. For eg: when A pairs with C. This repair mechanism is defective in HNPCC.