A 16-year-old adolescent girl presented with progressive walking imbalance, uncoordination of her limbs, impaired proprioceptive sensation distal to her wrists and ankles, and sensorineural hearing loss. Her evaluation revealed diffuse cerebellar atrophy, a demyelinating neuropathy, and hypergonadotropic hypogonadism. In this article, we present a systematic approach to a patient with early-onset ataxia, cerebellar atrophy, and demyelinating neuropathy.