The ataxias are a group of disorders that manifest with balance, movement, speech and visual problems. They can arise due to dysfunction of the cerebellum, the vestibular system and/or the sensory neurons. Genetic defects are a common cause of chronic ataxia, particularly common are repeat expansions in this group of conditions. Co-occurrence of cerebellar ataxia with neuropathy and vestibular areflexia syndrome has been termed CANVAS. Although CANVAS is a rare syndrome, on discovery of biallelic expansions in the second intron of replication factor C subunit 1 (RFC1) gene, we and others have found the phenotype is broad and RFC1 expansions are a common cause of late-onset progressive ataxia.

We aim to provide a review and update on recent developments in CANVAS and populations, where the disorder has been reported. We have also optimised a protocol for RFC1 expansion screening which is described herein and expanded phenotype after analysing late-onset ataxia patients from around the world.

共济失调是一组表现为平衡、运动、言语和视觉问题的疾病。它们可能由于小脑、前庭系统和/或感觉神经元的功能障碍而出现。遗传缺陷是慢性共济失调的常见原因，特别常见的是在这组疾病中的重复扩张。小脑共济失调与神经病变和前庭反射障碍综合征的共同发生被称为 CANVAS。尽管 CANVAS 是一种罕见的综合征，但在发现复制因子 C 亚基 1 ( RFC1 ) 基因的第二个内含子中的双等位基因扩增后，我们和其他人发现其表型广泛，RFC1扩增是迟发性进行性共济失调的常见原因。

我们的目标是对 CANVAS 和已报告该疾病的人群的最新发展进行回顾和更新。我们还优化了用于RFC1扩展筛选的协议，在分析了来自世界各地的迟发性共济失调患者后，本文描述了该协议并扩展了表型。