A first case of pituitary adenoma and LS was published in 2017 based on a 68-year-old subject with LS who was recognized as having a rapidly progressive corticotropinoma; she had an MLH1 germline mutation and an MSH6 somatic mutation, but also an MEN1 somatic mutation; IHC was negative for MLH1 and MSH6 [92]. This evidence concerns the gene MSH6 and Leigh syndrome.