An intronic GAA expansion in the FGF14 gene has recently been identified in several individuals with previously unexplained late-onset ataxia (PMID: 36516086, 36493768). The identification of this intronic expansion has led to the discovery of a new form of autosomal dominant hereditary ataxia, spinocerebellar ataxia type 27B (SCA27B). SCA27B is an autosomal dominant neurodegenerative disorder characterized by the onset of gait and appendicular ataxia in adulthood, usually around age 55 [MIM#620174]. About half of patients present with episodic features. The disorder is slowly progressive, and some patients may lose independent ambulation. Additional features include downbeat and horizontal nystagmus, diplopia, vertigo, and dysarthria. Re-analysis of a selected set of negative adult-onset ataxia cases in our laboratory has demonstrated FGF14 pathogenic expansions in ~20% of this cohort. We are excited to be the first lab in the US to begin offering clinical testing for SCA27B. FGF14 repeat expansion analysis has been added to our Ataxia Repeat Expansion Panel, making this panel more comprehensive. More details about our Ataxia Repeat Expansion Panel can be found here. FGF14 repeat expansion testing can also be ordered independently using our Single Gene Repeat Expansion Analysis.