The identification of rare mutations in sporadic haemorrhaging (11,12), and that common COL4A2 variants are a risk factor for deep ICH (13) and white matter hyperintensities (14) in the general population, underscore an important role for COL4A1/COL4A2 in common cerebrovascular disease and ICH. The gene discussed is COL4A1; the disease is cerebrovascular disorder.