In the AV node in HF there was a downregulation of key ion channel transcripts involved in AV node conduction: Scn10a responsible for Nav1.8; Cacna1d (Cav1.3) in part responsible for the L-type Ca2+ current, ICa,L; Cacna1g (Cav3.1) and Cacna1h (Cav3.2) responsible for the T-type Ca2+ current, ICa,T; and Kcnh2 (ERG) responsible for the rapid delayed rectifier K+ current, IK,r. The gene discussed is CACNA1D; the disease is hydrops fetalis.