Stable Leukoencephalopathy in a Patient With <i>ACTA2</i>-Associated Multisystem Smooth Muscle Disorder

A 14-year-old girl with recently diagnosed ACTA2 multisystem smooth muscle dysfunction syndrome (de novo R179H [G536A] ACTA2 variant) was referred for headaches. MRI revealed extensive increased T2 signal in the periventricular white matter (Figure 1), consistent with a stable leukoencephalopathy. CT angiogram revealed fusiform aneurysms of the petrous and cavernous internal carotid arteries bilaterally (Figure 2A) and short M1 segment of the middle cerebral arteries (Figure 2B). ACTA2 (OMIM#613834) is an autosomal dominant condition due to variants affecting the vascular smooth muscle alpha-actin gene. Characteristic features of ACTA2 and those present in our patient are presented in Table 1.1,2