Since HCN4 is highly expressed in cortical regions (including the hippocampus) specifically during infancy, and its expression rapidly declines with age (Brewster et al., 2007; Kanyshkova et al., 2009; Battefeld et al., 2012; Seo et al., 2015), HCN4 deficit may represent a potential mechanism for infantile forms of epilepsy. The gene discussed is HCN4; the disease is epilepsy.