CBS and Dravet syndrome: As reviewed recently (Szabo 2020), when cellular H2S levels are increased beyond an optimal concentration, H2S produce inhibitory bioenergetic effects (in principle, via inhibition of mitochondrial Complex IV, but also through other mechanisms) (Panagaki et al. 2019, 2020; Szabo 2020; Nicholls et al. 2013).1 Indeed, pharmacological inhibition or genetic silencing of CBS can restore mitochondrial function and cellular proliferation in DS fibroblasts (Panagaki et al. 2019) and it can improve neurological function in DS mice (Marechal et al. 2019).