FGF14-related episodic ataxia: delineating the phenotype of Episodic Ataxia type 9

Abstract

We report four patients from two families who presented attacks of childhood-onset episodic ataxia associated with pathogenic mutations in the FGF14 gene. Attacks were triggered by fever, lasted several days, and had variable frequencies. Nystagmus and/or postural tremor and/or learning disabilities were noticed in individuals harboring FGF14 mutation with or without episodic ataxia. These cases and literature data delineate the FGF14-mutation-related episodic ataxia phenotype: wide range of age at onset (from childhood to adulthood), variable durations and frequencies, triggering factors including fever, and association to chronic symptoms. We propose to add FGF14-related episodic ataxia to the list of primary episodic ataxia as Episodic Ataxia type 9.

Figure 1

Pedigrees of families A and B. Black upper right quadrant: episodic ataxia; black upper left quadrant: nystagmus; black lower right quadrant: tremor; black lower left quadrant: developmental delay/learning difficulties; *: mutation carrier; §: clinical examination performed by a neurologist, a neuro pediatrician or a geneticist.