SDHB and gastrointestinal stromal tumor: In our series, all MGMT-methylated cases but one were detected in the pathogenetically heterogeneous group of GIST WT for KIT and PDGFRA, and SDH-deficient GISTs were significantly enriched in MGMT-methylated cases; noticeably, with the limitations due to the small number of cases considered, SDH-deficient GISTs featured the highest prevalence of MGMT methylation (6/9, 67%) when compared to the other pathogenetically characterized GIST subgroups of our series (0/10, 0%, of PDGFRA-mutant GISTs; 1/15, 7%, of KIT-mutant GISTs; 1/5, 20%, of NF1-associated GISTs; Table 1).