SDHB and gastrointestinal stromal tumor: The SDHB gene mutation increases the risk of renal cell carcinoma, gastrointestinal stromal tumor (GIST), and breast and papillary thyroid carcinoma, and while patients with metastatic disease should be routinely tested for the presence of the predisposing SDHB mutation, there are no guidelines regarding the screening of asymptomatic SDHx gene mutation carriers.