Functional characterization of SDHB variants: Advancing succinate dehydrogenase biology and variant curation in hereditary paraganglioma

Germline variants in the gene encoding succinate dehydrogenase subunit B (SDHB) occur in around 10% of all patients with pheochromocytomas and paragangliomas (PPGLs). Diagnosis of these variants has profound implications not only for the patient but also their first-degree relatives in terms of risk for PPGLs and other SDHB-associated tumors (renal cell cancer and gastrointestinal stromal tumors). Appropriate surveillance of SDHB variant carriers is associated with reduced mortality from these cancers. Curation of disease-causing (pathogenic) variants from benign variants is therefore crucial; however, this task is often difficult for missense variants when their impact on biological function is unclear. In this issue of the JCI, Lee et al. have described a newly developed cellular complementation assay for SDHB function that may assist variant curation in clinical practice and thereby improve outcomes for patients inheriting these cancer-risk variants.