FH and neoplasm: Also, pseudo-hypoxia, the major phenomenon shown to date to mediate the tumorigenic ending of the loss of mitochondrial tumor suppressors, is a common mechanism for both SDH and FH mutations and in some tumors with SDHD or SDHB mutations, the hypoxia-inducible factor (HIF) pathway, and therefore an angiogenic reaction are activated due to high vascular density36.