In SDHx germline mutation carriers affected by a second hit, SDH loss of function leads to the accumulation of succinate in the tumor cells,68, 69, 70, 71, 72 which is the hallmark of tumorigenesis of these tumors This accumulation inhibits several α‐ketoglutarate dioxygenases, which are involved in the induction of the pseudohypoxia pathway and in epigenetic DNA modifications. The gene discussed is SDHB; the disease is neoplasm.