In a separate study focusing on point-mutation-negative HNPCC patients, 11% of cases harbored large rearrangements in four predisposition genes (MLH1, MSH2, MSH6, and PMS2) among which 29.6% affected the MSH2 gene (van der Klift et al., 2005). This evidence concerns the gene MLH1 and hereditary nonpolyposis colon cancer.