The most common single‐gene disorders identified to cause cSVD are cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) attributable to NOTCH3 mutations, CADASIL2 attributable to autosomal dominant HTRA1 mutations, and autosomal dominant COL4A1/2 disease.2 Here, HTRA1 is linked to CADASIL.