First, WMH constitutes the earliest and most prevalent neuroimaging hallmark of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), and HTRA1-related autosomal dominant CSVD, which could even be detected in advanced-stage CADASIL cases devoid of lacunar infarcts [30–32]. The gene discussed is HTRA1; the disease is CARASIL.