Potential differences in cognitive function and disability may have been masked by the fact that EGFr 1–6 patients had a higher educational level than the EGFr 7–34 participants, which has been shown to protect against the detrimental effects of brain damage in patients with CADASIL.31 In addition, older EGFr 1–6 patients were underrepresented because they were more likely to be too disabled to participate or to be deceased, or were diagnosed with CADASIL at a younger age. This evidence concerns the gene EGFR and CADASIL.