Functional downregulation of Ito in HF was reported by several studies in humans [11,35]), dogs [17,19,36] and rabbits [20,34] which were associated with decreased expression of Kv4.3 mRNA [11,35,37] and protein [36] levels without changing or even enhancing those of Kv1.4 [18]. The gene discussed is KCND3; the disease is hydrops fetalis.