CADM1 and attention deficit-hyperactivity disorder: Intriguingly, despite different strands of compelling evidence on the implicated roles of CADM1 gene in neurodevelopmental disruption (and likely symptom expression) and potential relevance to ADHD, no genetic variants of CADM1 have achieved the postulated genome-wide significance (P < 10-8) or been represented among the genome-wide association studies (GWAS) top hits—in either the meta-analysis or primary GWAS of ADHD (Demontis et al., 2019; Faraone and Larsson, 2019).