The term ataxia refers to a combination of symptoms and signs that result from damage to the cerebellum. Ataxia is not a diagnosis as it is caused by diverse conditions. Clinical history and examination dictate appropriate investigations, and with experience this is a rewarding approach to diagnosis. A case report in this issue highlights the importance of this clinical approach.1 The authors based their diagnosis of cerebrotendinous xanthomatosis (CTX) on the clinical observation of tendon xanthomata, early-onset cataracts and ataxia. Indeed, most of our patients with CTX attending the Sheffield Ataxia Centre were first diagnosed clinically and confirmed by the presence of raised serum cholestanol (without genetic testing). However, over the last 3 years, patients with a new diagnosis of CTX, made elsewhere and referred to our unit for management, have been diagnosed on the basis of genetic testing using next-generation sequencing with large panels of ataxia genes….