title: Risk of intracranial aneurysms in families with subarachnoid hemorrhage.
abstract: BACKGROUND
  Genetic factors may be important in the etiology of subarachnoid hemorrhage (SAH) and intracranial aneurysm (IA) formation. Several studies have reported the familial occurrence of SAH and IA, although in most cases asymptomatic family members were not studied with elective angiography. The examination of data from large sibships could provide important information about the frequency of IA occurrence in at-risk individuals and the mode of inheritance for familial SAH/IA.
  
  
  METHODS
  We reviewed published case series of sibships with SAH and at least four siblings, in which at least one sibling underwent elective angiography. Data were collected on age-of-onset, clinical events, presence of hypertension, angiographic findings, and outcome. Patients were classified as "affected" if they had a SAH or if an IA was detected by elective angiography, and "unaffected" if they were asymptomatic and had a negative angiogram.
  
  
  RESULTS
  Seven case series with 52 individuals (26 men and 26 women) met our inclusion criteria. The sibships ranged from 6 to 13 members. Most of the siblings (32 of 52, 61%) were asymptomatic, 18 (35%) had a SAH, and 2 (4%) had focal symptoms but no SAH. Elective angiography of 34 siblings showed an IA in 11 (32%) and was negative in 23 (68%). The overall rate of affecteds (SAH or IA) was 56%.
  
  
  CONCLUSIONS
  Based on data from these sibships, angiography of asymptomatic at-risk siblings demonstrated an IA in almost one-third of cases. Familial SAH/IA segregated with a pattern that was consistent with an autosomal dominant trait in this selected series of sibships, although other factors could produce these findings.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Alberts
authors.forename: A
authors.initials: A
authors.lastname: Quinones
authors.forename: C
authors.initials: C
authors.lastname: Graffagnino
authors.forename: A
authors.initials: A
authors.lastname: Friedman
authors.forename: A D
authors.initials: AD
authors.lastname: Roses
mesh_terms: D000328:Adult; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000209:etiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging / Q000235:genetics*