In particular, the mutation involving the Arg179 residue of ACTA2 is responsible for the multisystem smooth muscle dysfunction syndrome, a systemic disease characterized by aortic and cerebrovascular disease, fixed mydriatic pupils, hypotonic bladder, intestinal hypoperistalsis, pulmonary hypertension, and brain abnormalities [52]. Here, ACTA2 is linked to multisystemic smooth muscle dysfunction syndrome.