To identify the intervention targets for hemorrhagic stroke, investigatorshave identified several mutations in monogenetic stroke syndromes, including NOTCH3in cerebral autosomal dominant subcortical infarcts and leukoencephalopathy, COL4A1in COL4A1-related brain small-vessel disease, and KRIT1, CCM2 and PDCD10 in cerebralcavernous malformations (Li and Whitehead,2010; Lindgren, 2014;Rost et al., 2008). The gene discussed is COL4A1; the disease is hemorrhagic stroke.