Intracerebral hemorrhage (ICH), bleeding into the brain matter, is a particularly severe form of stroke that often leads to disability or death.  It remains difficult to prevent and to treat. Although hypertension and other factors may play a role in the onset of ICH, in many cases no specific cause can be identified.  Members of this network have independently shown that genetic susceptibility plays a role in some forms of ICH. Now, working together, the members of this network continue the systematic search for the genetic basis of ICH. The collaborative effort, among leaders in the field who have complementary areas of expertise, uses animal models, as well as samples from ICH patients, to investigate genes that control blood vessel function and maintenance in the brain. The ultimate objectives of network are to develop a diagnostic test for predisposition to ICH which might allow for preventive measures and effective treatment.