DRD4 and attention deficit-hyperactivity disorder: This interaction reflects a greater τ among ADHD subjects carrying DRD4-risk alleles in comparison to DRD4-4R homozygous (Kruskal–Wallis rank sum test, χ2 = 0.9562, df = 1, p-value = 0.01467, effect-size r = 0.44, and post hoc p-value: 0.03196; see Figure 3).