[Ruptured Aneurysm of an Aplastic or Twig-like Middle Cerebral Artery with Ring Finger Protein 213 Mutation:A Case Report].

Aplastic or twig-like middle cerebral artery(Ap/T-MCA)is a rare congenital anomaly, and several cases of ruptured cerebral aneurysm associated with Ap/T-MCA have been reported. Recently, the association of ring finger protein 213(<i>RNF213</i>)mutations with moyamoya disease has been identified, and the involvement of such mutations in intracranial arterial stenosis lesions other than those of moyamoya disease has been suggested. A 53-year-old woman with headache and nausea was admitted to our hospital. Computed tomography showed a diffuse subarachnoid hemorrhage. Cerebral angiography revealed left-sided Ap/T-MCA and two aneurysms in several fine arterioles. We performed trapping of these aneurysms. In the clinical course after surgery, she developed aphasia and mild motor paralysis. The patient was transferred to a rehabilitation hospital. The genetic screening revealed that she carried a heterozygous mutation of <i>RNF213</i>(c. 14429G>A p. R4810K). This is the first report of an association between Ap/T-MCA and <i>RNF213</i> mutations. In patients with the <i>RNF213</i> mutation, there is also the possibility of a progression of the intracranial arterial stenosis to other sites. Such patients should be carefully observed after the completion of their treatment.