Epilepsy, Generalized/genetics; Epilepsy, Generalized/physiopathology; Ion Channels/genetics; Ion Channels/physiology; Mutation; Seizures, Febrile/genetics; Seizures, Febrile/physiopathology; Age of Onset; Calcium Channels/genetics; Calcium Channels/physiology; Comorbidity; Epilepsy, Benign Neonatal/epidemiology; Epilepsy, Benign Neonatal/genetics; Epilepsy, Benign Neonatal/physiopathology; Epilepsy, Generalized/epidemiology; Genotype; Humans; In Vitro Techniques; Infant, Newborn; KCNQ2 Potassium Channel/genetics; KCNQ2 Potassium Channel/physiology; NAV1.1 Voltage-Gated Sodium Channel; NAV1.2 Voltage-Gated Sodium Channel; Nerve Tissue Proteins/genetics; Nerve Tissue Proteins/physiology; Phenotype; Potassium Channels, Voltage-Gated/genetics; Potassium Channels, Voltage-Gated/physiology; Receptors, Neurotransmitter/genetics; Receptors, Neurotransmitter/physiology; Research Design; Seizures, Febrile/epidemiology; Sodium Channels/genetics; Sodium Channels/physiology; Syndrome