Hereditary connective tissue diseases have different risks of aortic dissection depending on the causative gene. We report a family with no extravascular phenotype and a clinical diagnosis of familial thoracic aortic aneurysm and dissection, but genetic testing confirmed p.Tyr470Cys in TGFBR2, which is typically the responsible gene for Loeys–Dietz syndrome. Validation of the clinical diagnosis by genetic testing is warranted.