- Familial intracranial aneurysms are generally defined as the presence of two or more family members among first- and second-degree relatives with proven aneurysmal SAH (subarachnoid hemorrhage) or incidental aneurysms.
- The incidence of familial aneurysms among SAH patients is 6% to 20%.
- Familial intracranial aneurysm is defined as two or more blood relatives who possess intracranial aneurysms.
- The familial occurrence suggests a genetic component and the possibility of a genetically determined defect of the arterial wall.
- Several studies suggest that individuals with familial intracranial aneurysms are more likely to have multiple aneurysms and that these aneurysms are more likely to rupture at a smaller size than those patients with an isolated aneurysm.
- Treatment considerations are different for patients with familial aneurysms than for patients with an unruptured isolated aneurysm.
- The Familial Intracranial Aneurysm Study (FIA) has recruited a number of families and their goal is to identify genes that underlie the development and rupture of intracranial aneurysms.
- The National Institute of Neurological Diseases’ funded study is the largest genetic linkage study to date. The study includes 26 clinical centers that have broad experience in clinical management and imaging patients with intracranial aneurysms. The study will recruit 475 families with affected sib pairs or with multiple affected relatives through retrospective and prospective screening of potential subjects with an intracranial aneurysm.
- An important aspect of the genetic study is the study of environmental factors in disease risk such as smoking. Nearly 80% of patients with an Intracranial Aneurysm (IA) have a history of smoking at some time in their life. Not all individuals who smoke develop IA. Smoking may increase the risk of IA in for individual with specific genotypes at IA susceptibility loci.