Mutations in the ATPase domains of MSH2, MSH3 or MSH6, that render them defective in ATP binding, results in MMR deficiency in S. cerevisiae (Graham et al. 2018; Kumar et al. 2013), and mutations in the ATP-binding region of MSH2 are causative of HNPCC in humans (Lutzen et al. 2008; Drost et al. 2013). The gene discussed is MSH2; the disease is hereditary nonpolyposis colon cancer.