Homozygous Atp1a2 knock-out (KO) mice die immediately after birth [81], and recently biallelic loss of function variants in ATP1A2 have been reported in humans, resulting in death neonatally, with features of hydrops fetalis, microcephaly, arthrogryposis and extensive cortical malformations [82]. This evidence concerns the gene ATP1A2 and microcephaly.