Update on genetic testing for SCA27B

Many people with ataxia do not have a specific genetic diagnosis and the cause of their ataxia is unknown. In 2023, two papers were published which identified a genetic mutation that might be a common cause of late-onset ataxia (ataxia where the start of symptoms occurs relatively late in life). This type of ataxia has been named spinocerebellar ataxia 27B (SCA27B). 

The newly discovered mutation, which is thought to cause SCA27B, is found in a gene called fibroblast growth factor 14 (FGF14). In the human genome there are many different repeated sequences.  The number of repeats varies between people, and this does not normally cause a problem. However, sometimes if someone has too many repeats in a certain gene, this can cause a person to develop a condition, such as ataxia. This type of mutation is called a repeat expansion. Repeat expansions in different genes cause other types of ataxia; for example, Friedreich’s ataxia and Spinocerebellar ataxias (SCAs) 1, 2, 3, 6 and 7.  

In the two studies, researchers found that some people with ataxia of an unknown cause had a high number of repeats of the GAA sequence in a section of their FGF14 gene. Both studies show that the FGF14 repeat expansion could be a common cause of late-onset ataxia. The discovery of this genetic mutation may lead to more diagnoses for people with ataxia of unknown cause. To read more about the studies, read our article here.  

The test for the FGF14 mutation is not yet widely available. However, the Dr David Pellerin and Professor Henry Houlden at University College London are collaborating with the core genetic lab at Great Ormond Street Hospital in London to develop the test on a clinical basis, and expect to start offering the test by 2025. 

If you or someone you know has a genetic diagnosis of SCA27B, please let us at Ataxia UK know by email sparr-reid@ataxia.org.uk, so we can plan for future trials.

If your neurologist contacts researcher Dr David Pellerin, they can provide more information about genetic testing as part of their research project.

Contact details:
Dr David Pellerin and Professor Henry Houlden
Institute of Neurology, Queen Square, London WC1N 3BG
david.pellerin.21@ucl.ac.uk