Furthermore, KCNK9 subunits heterodimerized to a mutant KCNK3 subunit associated with PAH (e.g., G203D KCNK3) demonstrated increased K+ current activity compared to G203D KCNK3 associated with WT KCNK3 channel. This evidence concerns the gene KCNK9 and pulmonary arterial hypertension.