KCNJ10 and cerebellar ataxia: Indeed, loss of function variations (missense and nonsense mutations) in KCNJ10 (the gene encoding Kir4.1) causes an epileptic disorder known as EAST/SeSAME syndrome (Bockenhauer et al., 2009) characterized by early onset tonic-clonic seizures, sensorineural deafness, ataxia, intellectual disability, and electrolyte imbalance.