KCNH1 and Epileptic encephalopathy: Previously, a series of potassium-encoding genes were initially reported to be the severest phenotypes, such as developmental and epileptic encephalopathy (KCNA2, KCNT1, KCNT2, and KCNB1; Barcia et al., 2012; Torkamani et al., 2014; Syrbe et al., 2015; Gururaj et al., 2017) and syndromic neurodevelopment disorder (KCNN3 and KCNH1) (Kortum et al., 2015; Bauer et al., 2019).