Frequency and phenotype of GAA-FGF14 disease in bilateral vestibulopathy syndromes: insights from repeat expansion carriers, including a case of co-occurrence with RFC1-related CANVAS

OBJECTIVES: Intronic FGF14 GAA repeat expansions cause spinocerebellar ataxia 27B (SCA27B) / GAA-FGF14 disease. Bilateral vestibulopathy (BVP) has been reported as a recurrent feature of this disease. Here, we aimed to determine whether GAA-FGF14 expansions represent a common cause of primary BVP syndromes.

Audiologists and vestibular clinicians should be aware that GAA-FGF14 repeat expansions can underlie bilateral vestibulopathy, and rare co-occurrence with RFC1-CANVAS is possible, but genetic testing protocols are not yet standardised — no immediate practice change is warranted pending larger replication studies.

Identifying genetic causes of bilateral vestibulopathy, such as GAA-FGF14 and RFC1 expansions, is critical for accurate diagnosis, counselling, and future targeted therapies in a population that is often underdiagnosed.

1. 01GAA-FGF14 repeat expansions were assessed for frequency in patients with bilateral vestibulopathy syndromes.
2. 02The study characterises the clinical phenotype of GAA-FGF14 disease in this specific vestibular population.
3. 03A rare case of GAA-FGF14 disease co-occurring with RFC1-related CANVAS is reported for the first time.
4. 04Findings highlight genetic overlap and diagnostic complexity in hereditary vestibulopathy.
5. 05Results support including FGF14 repeat expansion testing in the diagnostic workup of unexplained bilateral vestibulopathy.

PMID

42178418

DOI

10.1007/s00415-026-13867-1.

Journal

Journal of Neurology

Publication type

research_article

Evidence level

4

Population

Patients with bilateral vestibulopathy syndromes, including repeat expansion carriers for GAA-FGF14 and RFC1 variants

Intervention

Genetic screening for GAA-FGF14 repeat expansions in bilateral vestibulopathy