To establish whether PAH-associated ATP13A3 variants are pathogenic, we assessed the functional impact of five PAH-associated missense protein variants (L675V, M850I, V855M, R858H, and L956P; Supplementary material online, Figure S7A) in different EC models, comparing these with ATP13A3 wild-type (ATP13A3-WT) protein and an artificial transport dead mutant protein with a D498N substitution in the catalytic autophosphorylation domain. The gene discussed is ATP13A3; the disease is pulmonary arterial hypertension.