associated with the 7-repeat allele of the DRD4 receptor gene52; measurements of response inhibition with the 10/10 repeat genotype on DAT153; RT data and the absence of the ADHD-risk allele on the DRD4 gene54–56; and homozygosity for the 10-repeat allele of DAT1 with left-sided inattention and enhanced methylphenidate response.57,58 A significant genomewide linkage signal was also reported for motor timing on 2q21.1 and digit span on 13q12.11.59 However, these studies need replication (e.g., Manor et al.55).
