H2S is now considered as a major gasotransmitter in the brain, which plays a role in synaptic transmission (Kamat et al., 2015) and its increased production resulting from CBS triplication has been suggested to contribute to the cognitive phenotype of DS patients (Kamoun, 2001; Kamoun et al., 2003; Szabo, 2020). The gene discussed is CBS; the disease is Dravet syndrome.