SDHB and neoplasm: Moreover, paraganglioma patients with SDH or FH-deficiency associated DNA CIMP had a much worse prognosis compared with other molecular subtypes, indicating that epigenetic dysregulation in SDH or FH-mutant patients contributes to tumor development and progression.89 Thus, genetic mutations in FH and SDH can lead to accumulation of fumarate and succinate, respectively, which drives tumorigenesis via epigenetic deregulation.