MSH6 and Leigh syndrome: Mutations in Lynch syndrome (LS) genes (MLH1, MSH2, PMS2, MSH6) were identified in 11 cases, including one case with mutations in both MSH6 and RAD50. Six MSH6 mutations were detected among FBC cases, but this rate was not significantly higher than in ExAC control individuals (0.28 vs. 0.13%).