DRD4 and attention deficit-hyperactivity disorder: Additionally, the DRD4 48 bp 7-R allele polymorphism has been associated with novelty-seeking (Schinka et al., 2002), impulsivity (Eisenberg et al., 2007; Congdon et al., 2008; Varga et al., 2012), risk behavior (Dreber et al., 2009; Kuhnen and Chiao, 2009; Roussos et al., 2009) and ADHD (LaHoste et al., 1996; Faraone et al., 1999).