A STUDY OF INBREEDING AND KINSHIP IN INTRACRANIAL ANEURYSMS IN THE SAGUENAY LAC-SAINT-JEAN REGION (QUEBEC, CANADA)

The genealogies of 533 individuals with an intracranial aneurysm (IA) born in the Saguenay-LacSaint-Jean region, a geographically isolated a rea located in northeastern Quebec, were reconstructed using a populat ion-based register. A control group consisting of three individuals of the same sex and born on the same day and in the same municipality th an the IA patients was created; the genealogies of the 1599 controls w ere also reconstructed. The coefficients of inbreeding and kinship wer e calculated. Familial aggregation, i.e. the presence of IA in two or more first- to third-degree relatives, was also sought. The mean inbre eding coefficient was lower in the IA group than in the control group (7.92 x 10(-4) versus 10.04 x 10(-4)). The mean kinship coefficient wa s higher in the IA group than in the control group (2.17 x 10(-4) vers us 1.55 x 10(-4)). Forty-eight IA patients (90%) were first-degree rel atives compared to only 1.9 % of the control individuals. The proporti on of individuals showing familial aggregation was higher in the IA gr oup than in the control group (29.8% and 18.6% respectively). These re sults strongly suggest that some IB are genetically determined in this population.