MRIs of patients with CADASIL and cysteine-involving (C174R, 66/F, A-C) or cysteine-sparing (R75P, 67/F, D-F) NOTCH3 mutations are shown. Axial fluid attenuation inversion recovery (FLAIR) images showing similar diffuse frontal, parietal subcortical white matter changes (C, F), and external capsule involvements (B, E). However, anterior temporal lobe involvement is seen only in the patient with a cysteine-involving NOTCH3 mutation (A) and is absent in the patient with a cysteine-sparing NOTCH3 mutation (D). CADASIL, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy; MRI, magnetic resonance imaging.