SDHB and neoplasm: Finally, we assessed the impact of SDHx mutations on MGMT methylation in a tumour dataset of PPGL (online supplemental figure S2) (N=190).16 SDH-deficient PPGL demonstrated a significant (p<0.00001) increase in MGMT promoter methylation compared with pSDH PPGL (mean methylation in dSDH PPGL 15.5%; STD 11.3% vs pSDH PPGL 6.6%; STD 4.9%).