Familial intracranial aneurysms. Six cases among 13 siblings.

The authors present a family of 13 siblings: six are proven to have had intracranial aneurysms, five have had elective cerebral angiography with normal findings, and two have refused angiography. Of the six aneurysm cases, two had disabling and one had fatal subarachnoid hemorrhages; three underwent successful clipping of their aneurysms which were discovered by elective angiography. It is concluded that the two remaining patients who have refused angiography have a 50% statistical chance of harboring a potentially lethal aneurysm, for in this family the occurrences of six proven cases among 11 siblings studied is consistent with a dominant Mendelian inheritance.