Because of their central role in the acquisition of tumour hallmarks by SDH- and FH-deficient cells, succinate and fumarate are now referred to as “oncometabolites”, as 2-hydroxyglutarate, the organic acid generated by mutant isocitrate dehydrogenase mutants in gliomas and acute myeloid leukaemia [58]. The gene discussed is SDHB; the disease is neoplasm.