Genetic testing for ACTA2 mutations should be considered in patients with one or more of the following conditions: early onset thoracic aortic dissection (type A or B dissection); family history of acute aortic events; peripartum aortic dissection; clinical features associated with ACTA2 mutation (e.g., early-onset stroke, livedo reticularis, iris floccule, or other extra-aortic features associated with multisystem smooth muscle dysfunction syndrome). The gene discussed is ACTA2; the disease is multisystemic smooth muscle dysfunction syndrome.