Loss-of-function mutations in the KCNJ2 gene are responsible for the rare Andersen-Tawil syndrome (OMIM 170390) a condition characterized by long QT-syndrome, cardiac arrhythmia, skeletal abnormalities, periodic paralysis, mood disorders, and seizures (Haruna et al., 2007; Chan et al., 2010). This evidence concerns the gene KCNJ2 and mood disorder.