AIM: Recently, we reported a previously unrecognized symptom constellation 
comprising epilepsy, ataxia, sensorineural deafness, and tubulopathy (EAST 
syndrome) associated with recessive mutations in the KCNJ10 gene. Here, we 
provide a detailed characterization of the clinical features of the syndrome to 
aid patient management with respect to diagnosis, prognostic counselling, and 
identification of best treatment modalities.
METHOD: We conducted a retrospective review of the detailed neurological and 
neuroradiological features of nine children (four females, five males; age range 
at last examination 6-20y) with genetically proven EAST syndrome.
RESULTS: All children presented with tonic-clonic seizures in infancy. Later, 
non-progressive, cerebellar ataxia and hearing loss were noted. Whilst seizures 
mostly responded well to treatment, ataxia proved to be the most debilitating 
feature, with three patients non-ambulant. All available magnetic resonance 
imaging (MRI) revealed subtle symmetrical signal changes in the cerebellar 
dentate nuclei. Moreover, four patients had a small corpus callosum and 
brainstem hypoplasia, and three had a small spinal cord. Regional quantitative 
volumetric analysis of the images confirmed the corpus callosum and brainstem 
hypoplasia and showed further patterns of variation from the norm.
INTERPRETATION: The neurological features of EAST syndrome appear to be 
non-progressive, which is important for prognostic counselling. The spectrum of 
EAST syndrome includes consistent abnormalities on brain MRI, which may aid 
diagnosis. Further longitudinal documentation is required to determine the true 
natural history of the disorder.