FGFR3 and Leigh syndrome: Some hereditary cancers are misclassified as sporadic, although their identification might have consequences for both patients and their family members, because this information would prompt germline testing and, if positive, screening for LS-related malignancies.27 Our data suggest that the finding of an FGFR3 R248C somatic mutation is a potential biomarker for LS and its identification in a patient should prompt germline testing for LS.