Paroxysmal Ataxia: A Characteristic Feature of FGF14 Repeat Expansion (SCA27B)
Cendrine Foucard1, Marie Belley1, Aude Sangare1
1From the Assistance Publique-Hôpitaux de Paris (C.F., M.B., A.S., E.R.), DMU Neurosciences, Hôpital Pitié-Salpêtrière; Sorbonne Université (C.F., A.S., E.R.); Inserm U1127 (A.S., E.R.), CNRS UMR 7225, UM 75, Institut du Cerveau, Paris; Laboratoire de Génétique Médicale (C.B.), Hôpitaux de Brabois - CHRU de Nancy; INSERM-U1256 NGERE (C.B., M.R.), Université de Lorraine; Service de Neurologie (M.R.), CHRU de Nancy; and Service de Génétique Clinique (M.R.), CHRU Nancy, France.
Objectives:
Paroxysmal ataxia is typically characterized by early-onset attacks of cerebellar ataxia. Late-onset cerebellar ataxia (LOCA) comprises a group of neurodegenerative disorders mainly characterized by adult-onset progressive cerebellar ataxia. A deep intronic expansion of a GAA triplet in the FGF14 gene encoding fibroblast growth factor 14 has recently been identified as a frequent cause of LOCA.
Methods:
We describe a patient with paroxysmal ataxia/dysarthria due to a FGF14 repeat expansion and 3 affected family members.
Results:
The 4 patients had paroxysmal ataxia/dysarthria occurring between 45 and 50 years as the initial manifestation of a FGF14 repeat expansion. The index case was investigated in detail. We have provided a video showing one of her paroxysmal episodes that could be triggered by alcohol, coffee, exertion, emotion, or cigarette smoking. Brain MRI revealed mild cerebellar atrophy, and oculography showed a subclinical downbeat nystagmus. Treatment with acetazolamide resulted in remarkable improvement.
Discussion:
Paroxysmal dysarthria/ataxia should prompt the clinician to test for FGF14 repeat expansion/SCA27B, especially when the paroxysmal attacks are associated with late-onset cerebellar ataxia and/or a family history consistent with a dominant disorder.
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