Age distribution of the first TIA/stroke in patients with hereditary TTP or SCA. Data for 116 SCA patients are from Powars et al.¹⁴  Forty of the 155 patients (26%) from our review of case reports had TIA/stroke; 3 of the 40 patients were excluded from this figure because their age at the time of their TIA/stroke was not reported. Among the SCA patients, 116 of the 1056 patients (11%) were reported to have overt stroke; silent strokes were not reported. Most patients with hereditary TTP (75%) and SCA (75%) had TIA/stroke prior to 30 years of age.