In a recent review of more than 215 cases of AxD with GFAP mutation, AxD was divided into 2 groups: type I was characterized by early onset, seizures, megalencephaly, and typical leukodystrophy as MRI features, and type II with a later age at onset characterized by brainstem features and atypical MRI findings [13]. The gene discussed is GFAP; the disease is Alexander disease.