For the total sample having no missing data (n = 336; 185 ADHD probands and 151 controls), the subjects with the GG genotype in the GRM7 rs37952452 polymorphism also showed higher mean T-scores for omission errors on the CPT than did those with the GA or AA genotype (t = 2.17, p = 0.034). Here, GRM7 is linked to attention deficit-hyperactivity disorder.