Monogenetic diseases causing ischemic stroke were observed in five patients (2.9%): In three patients with lacunar stroke (1.7%), we identified pathogenic variants in NOTCH3 causing cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The gene discussed is NOTCH3; the disease is cerebral arteriopathy with subcortical infarcts and leukoencephalopathy.