A retrospective study of 36 children with ACC coming from southern Brazil, where the TP53 gene mutation (TP53 p.Arg337His) prevalence is significantly increased, included IHC and NGS for MLH1, MSH2, MSH6, and PMS2; 8.57% of them had altered MLH1 (N = 2 cases), respective of MSH6 (N = 1) confirming LS, a prevalence that is higher than the prevalence of LS-associated MMR anomalies among global subjects with EC and CRC [26]. The gene discussed is PMS2; the disease is Leigh syndrome.