[Familial incidence of intracranial aneurysms]

On the inheritance of intracranial aneurysms

BACKGROUND AND PURPOSE

The familial occurrence of intracranial aneurysms suggests the presence of a genetically determined underlying arteriopathy. The pattern of inheritance in these families usually is not known.

METHODS

A family with seven members with intracranial aneurysms is described and, from the literature before 1994, a total of 238 families with 560 affected members (56% female and 44% male) with intracranial aneurysms not associated with a known heritable disease are reviewed. A segregation analysis was performed on 73 of these families.

RESULTS

Two members were affected in the great majority of families (79%); five or more members were reported in only eight families (3%). The most common affected kinship was among siblings. Angiographic screening in 12 families detected an intracranial aneurysm in 29% of 51 asymptomatic relatives. Segregation analysis revealed several patterns of inheritance that were consistent with the compiled pedigrees, but no single mendelian model was the overall best fitting, suggesting that genetic heterogeneity may be important. Twenty-two percent of siblings of male probands had an intracranial aneurysm compared with 9% of siblings of female probands (P = .003).

CONCLUSIONS

Genetic heterogeneity may be important in the genetics of intracranial aneurysms. In families with intracranial aneurysms, siblings of an affected male proband may be at a higher risk of developing an aneurysm than siblings of an affected female proband. Screening for intracranial aneurysms in asymptomatic relatives should be considered in families with two or more affected members. In most families, the nature of the underlying arteriopathy remains obscure.

Familial subarachnoid hemorrhage in east Finland, 1977-1990

The familial occurrence of cerebral aneurysms in a defined clinical group of 1150 patients from a defined catchment area was studied. Two or more proven aneurysmal subarachnoid hemorrhage (SAH) patients within the same family were included. Of these 1150 patients, 113 (10%) had a proven familial occurrence of aneurysmal SAH. These 113 patients form 91 SAH families with a total of 203 aneurysm patients. Fifty-four percent of the patients were female, and the mean age in female patients was 49 years and in male patients was 44 years. In 23% of the families, three or more members were identified as having cerebral aneurysms. Middle cerebral artery aneurysms were the most common type (47%). Based on the high incidence (10%) of familial intracranial aneurysms among SAH patients, a prospective study of healthy family members for incidental intracranial aneurysms was performed, with positive findings of 12%.

[Intracranial saccular aneurysm: report of 3 cases in a same family]

The authors report the cases of three patients from the same family, all with intracranial saccular aneurysm (left carotid artery, anterior communicating artery, and middle cerebral artery). All three patients were operated on with good recovery and no complications. The authors call attention for some etiopathogenic aspects of familial saccular aneurysms.

Familial intracranial aneurysms

The authors report seven individuals from two families, all of whom had aneurysmal subarachnoid hemorrhage. These cases and all reported cases of familial aneurysms (243 aneurysms in 177 patients from 74 families) were submitted to computer-aided multivariate analysis to determine if the aneurysms or the patients who harbor them differ from sporadic aneurysm cases. Familial aneurysms rupture at a smaller size (mean diameter 10.5 mm), and when the patient is younger (mean age 42.3 years and decennial age at peak incidence 40 to 49 years). There is a similar sex distribution (male to female ratio 48:52), a similar incidence of multiple aneurysms (21.5%), and a similar predominance of females over males with multiple aneurysms (2.2:1). Anterior communicating artery aneurysms occur less often in familial cases (19%) than in sporadic cases. In sibling pairs the aneurysms occur at the same or at mirror sites, and rupture within the same decade twice as frequently as randomly selected nonfamilial aneurysm patient pairs. The occurrence of aneurysms at identical and mirror sites is more frequent in familial cases and appears to be a function of the degree of kinship between affected individuals. These observations suggest a genetic basis for the pathogenesis of familial intracranial aneurysms.