The team at the Sheffield Ataxia Centre, led by Prof Marios Hadjivassiliou, has been investigating whether faulty genes called RFC1 seen in a condition called CANVAS (cerebellar ataxia, neuropathy and vestibular areflexia syndrome) are present in people with ataxia of unknown cause. The RFC1 gene is needed for DNA repair in cells. A fault involving an expansion of the building blocks in the RFC1 protein, in a repeating pattern, leads to symptoms such as ataxia, cognitive decline, chronic cough, involuntary movement and muscle twitching.
The team found that in 38 participants diagnosed with cerebellar ataxia and sensory ganglionopathy (SG) – loss of sensations such as touch and reflexes – 71% of them had faulty RFC1. However, in 54 participants with idiopathic sporadic ataxia without SG, none possessed the faulty RFC1 gene.
Importantly, the study has shown that the presence of sensory ganglionopathy in people with ataxia is a good indicator that someone may have CANVAS. This finding is helpful in informing clinicians as to whether a test for RFC1 is needed. Since CANVAS with faulty RFC1 genes is now thought to be one of the most common recessive ataxias after Friedreich’s Ataxia and Spastic Paraplegia Type-7, more efficient screening methods for the presence of faulty RFC1 are important for diagnostic progress.