FH and cancer: Notably, in human cancers caused by mutations in IDH1, FH or SDH, the accumulation of metabolites in the TCA cycle, such as succinate and fumarate, is also frequently observed (Chowdhury et al., 2011; Dang et al., 2009; Ge et al., 2022; Sulkowski et al., 2020; Xu et al., 2011).