Several types of RNA can trigger MDA5-dependent responses in experimental settings (Malathi et al., 2007, 2010; Pichlmair et al., 2009; Luthra et al., 2011; Züst et al., 2011; Feng et al., 2012; Triantafilou et al., 2012) but it remains unclear which RNAs serve as natural MDA5 agonists during virus infection. The gene discussed is IFIH1; the disease is viral infectious disease.