NCAM2 and attention deficit-hyperactivity disorder: Several (Fig. S11) relate to ion channels (e.g., KCNIP1, KCNK10, CACNA1E, and CACNB4) or are involved in cell adhesion (e.g., NCAM2, NRXN1, CNTNAP2, and CDH22), both previously implicated in ADHD or other psychiatric traits54–58.