SDHD and neoplasm: SDHD, SDHB and SDHC mutations are a basis for a series of molecular procedures leading to the abnormal stabilization of hypoxia-inducible factors (HIF) under normoxic or hypoxic conditions or pseudo-hypoxia (via inactivation of SDH, accumulation of succinate, inhibition of prolyl-4-hydroxylases and subsequent HIF hydroxylation), thus, encouraging cell proliferation, angiogenesis and tumor genesis 23.