Repeated de novo aneurysm formation after anastomotic surgery: Potential risk of genetic variant RNF213 c.14576G>A

Background: De novo aneurysm formation after intracranial anastomotic surgery is a relatively rare complication with fewer than 20 reported cases, and the mechanism is still unclear. Case Description: A 63-year-old male treated for symptomatic internal carotid artery occlusion developed de novo aneurysms twice after anastomoses first of the superficial temporal artery-middle cerebral artery and second of the external carotid artery-radial artery-middle cerebral artery over a 10-year period. The first de novo aneurysm was successfully resected with pathological diagnosis of true aneurysm. The second de novo aneurysm thrombosed naturally after gradual growth. Genetic testing of the patient revealed the c.14576G>A (p.R4859K) variant in ring finger protein 213, which is a susceptibility gene for moyamoya disease. Conclusions: This genetic variant was probably involved in the repeated de novo aneurysm formation, and this case represents a rare phenotype of the genetic variant.