Recently, we described children presenting with a unique constellation of symptoms, namely epilepsy, ataxia, sensorineural deafness and tubulopathy, which we assigned the acronym EAST syndrome. Genetic investigations in an informative kindred with four affected children revealed the underlying genetic basis as recessive mutations in the potassium channel KCNJ10. Affected children identified so far all presented with grand-mal seizures in infancy and were subsequently found to have ataxia and sensorineural deafness. Biochemical investigations show a hypokalaemiac, hypochloraemic metabolic alkalosis with hypomagnesaemia and hypocalciuria, a constellation typical for impaired salt-transport in the distal convoluted tubule. Investigation of EAST syndrome reveals the role of KCNJ10 in human physiology and pathophysiology.