DNA Mismatches (IMAGE) Johns Hopkins Medicine Caption Mismatch repair deficiency refers to a characteristic of some cancer cells that create a large number of mutations, or changes, in certain genes when their mismatch repair proteins are unable to correct mistakes made when DNA is copied and passed on to daughter cells. Credit Andrew H. Lee Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.