SCN3A and Brain atrophy: Brain atrophy has been reported in four patients with the L1324P in SCN2A (Begemann et al., 2019; Dimassi et al., 2016; Matalon, Goldberg, Medne, & Marsh, 2014; Wolff et al., 2017) and two patients with I875T in SCN3A (Zaman et al., 2018), suggesting a potential variant‐specific effect on brain structural development.