SDH-deficient tumors are often an indicator of a genetic, tumor-predisposition syndrome, associated with germline mutations in any of the SDHx subunits: SDHA, SDHB, SDHC, SDHD or rarely SDHAF2. In the case of CT, epimutation of SDHC promoter locus is the cause. This evidence concerns the gene SDHAF2 and BAP1-related tumor predisposition syndrome.