Typically, biallelic AAGGG250–2000 expansions in intron 2 of RFC1 cause Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome (CANVAS), a disorder that affects sensory neurons, the vestibular apparatus, and the cerebellum [92, 93]. The gene discussed is RFC1; the disease is cerebellar ataxia.