Bourcier R, et al. – In this study involving ~130 patients from 64 families, researchers examined the concordance of aneurysm size at time of rupture in familial intracranial aneurysms (IAs). The ratio between the largest and the smallest aneurysm size at time of rupture was calculated in pairs of affected relatives with aneurysmal subarachnoid hemorrhage. No difference was found between the proportion of families who both had IA at time of rupture < 7 mm or both ≥ 7 mm and the proportion of those families with one patient with an IA < 7 mm and another with an IA ≥ 7 mm. Overall, the repeatability in aneurysm size at rupture within familial IAs was 0.10. Within familial IAs, there is no good concordance in aneurysm size at rupture. According to findings, size of a ruptured IA in a family member should not have a significant effect on the management of a familial unruptured IA in a relative.