ST3GAL3 and attention deficit-hyperactivity disorder: The most notable example is ST3GAL3: common variation in this gene has also been identified as a top GWAS hit for ADHD (Demontis et al., 2019; Klein et al., 2019), rare mutations of ST3GAL3 associate with cognitive and motor developmental delays (Khamirani et al., 2021), and ST3GAL3 knockout in mice results in profound cognitive deficits and hyperactivity due to myelination disruption (Rivero et al., 2021).