Epilepsy, Idiopathic Generalized 18, is also known as epilepsy, idiopathic generalized, susceptibility to, 18. An important gene associated with Epilepsy, Idiopathic Generalized 18 is HCN4 (Hyperpolarization Activated Cyclic Nucleotide Gated Potassium Channel 4). Affiliated tissues include brain and heart, and related phenotypes are delayed speech and language development and bradycardia