RISK OF INTRACRANIAL ANEURYSMS IN FAMILIES WITH SUBARACHNOID HEMORRHAGE

Background: Genetic factors may be important in the etiology of subara chnoid hemorrhage (SAH) and intracranial aneurysm (IA) formation. Seve ral studies have reported the familial occurrence of SAH and IA, altho ugh in most cases asymptomatic family members were not studied with el ective 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. M ethods: 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, pre sence of hypertension, angiographic findings, and outcome. Patients we re classified as ''affected'' if they had a SAH or if an IA was detect ed by elective angiography, and ''unaffected'' if they were asymptomat ic and had a negative angiogram. Results: Seven case series with 52 in dividuals (26 men and 26 women) met our inclusion criteria. The sibshi ps ranged from 6 to 13 members. Most of the siblings (32 of 52, 61%) w ere asymptomatic, 18 (35%) had a SAH, and 2 (4%) had focal symptoms bu t 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 I A) was 56%. Conclusions: Based on data from these sibships, angiograph y of asymptomatic at-risk siblings demonstrated an IA in almost one-th ird of cases. Familial SAH/IA segregated with a pattern that was consi stent with an autosomal dominant trait in this selected series of sibs hips, although other factors could produce these findings.