The Na+/H+ exchanger 6 and 9 (NHE6/9 or SLC9A6/9) has been identified as candidate gene of interest for attention deficit hyperactivity disorder (ADHD) (Lasky-Su et al., 2008) and ASD (Morrow et al., 2008). This evidence concerns the gene SLC9A6 and attention deficit-hyperactivity disorder.