The function of some of the transcripts (Fat1, Fermt2, Fign, Lrch1, Tmem182) is either unknown or has an unknown relevance for the AV node; some transcripts are involved in heart development (Meis1, Id2, Tbx3); two transcripts are known to be involved in HF (Camk2d, Myocd); and one transcript (Scn10a) is known to modulate AV node conduction (Table 1). The gene discussed is ID2; the disease is hydrops fetalis.