Spontaneous distal middle cerebral artery aneurysm in a young male with full mutation of the fragile X syndrome with a high-functioning phenotype: illustrative case.

backgroundFragile X syndrome (FXS) is a genetic disorder that typically presents with neurodevelopmental abnormalities. Patients with FXS can present with signs and symptoms of connective tissue disorder (CTD) and occasionally with vascular disease. However, cerebrovascular disease is not well documented in these patients, and it is unknown whether there is a direct link between abnormal levels of fragile X protein (FMRP) and its mRNA. OBSERVATIONS: Here, the authors present a rare case of an adult male with full mutation FXS of a high-functioning phenotype who presented with syncope, and on further evaluation, a fusiform dissecting aneurysm of the distal middle cerebral artery was identified. The patient was treated for the aneurysm and recovered successfully. LESSONS: Previous clinical evidence suggests that there might be an association between FMRP and increased mRNA levels on CTD and vascular pathologies in patients with FXS. This leads the authors to believe that their patient's previous FXS diagnosis might have played a role in the spontaneous aneurysm and presents a novel area of inquiry in the clinical and pathological manifestations of this disease. Therefore, screening for underlying FXS genetic abnormalities in patients with CNS aneurysms and screening for aneurysms in those with these mutations might need to be considered. https://thejns.org/doi/10.3171/CASE24889.