Selak et al. has recently shed light on the mysterious connection between tumors and SDH/FH [5]; they showed that the hypoxia-inducible factor (HIF)–mediated signaling pathway, known to be tumorigenic in von Hippel Lindau syndrome, also plays a role in SDH and FH deficiency (Figure 1) [5]. Here, FH is linked to von Hippel-Lindau disease.