For example, APOE, SLC5A7, and CHRNA4 are all associated with the neurotransmitter acetylcholine, which has been associated with cognitive development (McKinnon and Nathanson, 1995) and with visuospatial attention, ADHD, and distractibility (Manuck et al., 2000; Manor, 2002; Störmer et al., 2012; Markant et al., 2014). The gene discussed is CHRNA4; the disease is attention deficit-hyperactivity disorder.