Fragile X-associated tremor/ataxia syndrome (FXTAS) is a rare neurodegenerative disorder characterized by adult-onset progressive intention tremor and gait ataxia. The disease is Monarch Disease Ontology term MONDO_0010382 (fragile X-associated tremor/ataxia syndrome). Also known as: FXTAS syndrome, Fragile X tremor/ataxia syndrome, X-linked dominant.