The project will involve multiple units within our Institute (Neurosurgery, Cerebrovascular Diseases, Neurology IV), as well as additional neurosurgical centers across Italy, for the enrollment of patients with saccular intracranial aneurysms (sIA), both ruptured and unruptured. Based on predefined inclusion and exclusion criteria, the recruitment target over a two-year period is 400 patients with sIA (200 ruptured, 200 unruptured) and 200 healthy controls. The study will not alter clinical practice: treatment decisions for unruptured sIA will be made independently by vascular teams according to routine standards. For each enrolled subject, anonymized clinical data will be collected (age, sex, BMI, lifestyle habits, family history, comorbidities, aneurysmal parameters) to build an integrated database within the Biorepository. Peripheral blood samples will be obtained for genomic analyses, and when available (e.g., during clipping procedures or lumbar puncture), aneurysm wall tissue and/or cerebrospinal fluid (CSF) samples will be collected for expression studies. All materials and data (clinical/genetic) will be coded and stored at the Cryobank of the Fondazione IRCCS Istituto Neurologico Besta. Genomic analyses: a pathway-based Genome-Wide Association Study (GWAS) is planned. Phase I: Genotyping of 200 patients (100 with ruptured sIA, 100 with unruptured sIA) and 100 healthy controls, with combined analysis of genetic data and environmental factors related to rupture risk. Phase II: Validation in an additional cohort of 200 patients (100 ruptured, 100 unruptured) and 100 controls to confirm the associations of identified SNPs.