Results: Three familialfactors (cF1-3), showing substantial familial overlap with ADHD,captured the familial covariation of ADHD with nine cognitive-ERP measures.cF1 loaded on IQ, mean reaction time (MRT), and reaction-timevariability (RTV); cF2 on DSF and DSB; and cF3 on numberof errors and ERPs of inhibition and error processing. The gene discussed is ATP6AP1; the disease is attention deficit-hyperactivity disorder.