This study shows that mice with mutant type IV collagen α1 protein are susceptible to trauma-induced hemorrhage and stroke. Building on this finding is the discovery that a variant of the human orthologue is associated with small-vessel disease and hemorrhagic stroke. This study shows that mice with mutant type IV collagen α1 protein are susceptible to trauma-induced hemorrhage and stroke. Stroke is a leading cause of death and serious long-term disability in developed nations. 1 Survivors often have a severely diminished quality of life, require long-term care, and are at high risk for recurrence. 1 Intracerebral hemorrhage accounts for 10 to 15 percent of strokes and is a particularly severe form of stroke, with disproportionately high rates of death and long-term disability. 1 Hypertension and amyloid angiopathy are important risk factors associated with intracerebral hemorrhage; other risk factors include vascular malformations, coagulation abnormalities, and the use of sympathomimetic drugs. 2 However, intracerebral hemorrhage often occurs in the absence of a history of known risk . . .