Organizational inefficiency and inattention are speculated to be the reason for executive deficit (ED) of ADHD probands. Even with average IQ, probands often perform poorly due to higher inattention. Pharmacotherapy, cognitive behavioural therapy, and counselling provide only symptomatic relief. Several candidate genes showed involvement with ADHD; the most consistent are dopamine receptor 4 (DRD4) and solute carrier family 6 member 3 (SLC6A3). We analyzed association of rarely investigated DRD4 and SLC6A3 variants with ADHD core traits in Indo-Caucasoid probands. ED, inattention, organizational efficiency, and IQ were measured by Barkley Deficit in Executive Functioning-Child & Adolescent scale, DSM-IV-TR, Conners’ Parent Rating Scale-revised, and WISC respectively. Target sites were analyzed by PCR, RFLP, and/or Sanger sequencing of genomic DNA. DRD4 variants mostly affected inattention while SLC6A3 variants showed association with IQ. Few DRD4 and SLC6A3 variants showed dichotomous association with IQ and inattention. DRD4 Exon3 VNTR >4R showed negative impact on all traits excepting IQ. Inattention showed correlation with attention span, organizational efficiency, and ED, while IQ failed to do so. We infer that IQ and attention could be differentially regulated by dopaminergic gene variants affecting functional efficiency in ADHD and the two traits should be considered together for providing better rehabilitation.

组织效率低下和注意力不集中被认为是ADHD先证者执行缺陷（ED）的原因。即使智商水平一般，由于注意力不集中，先证者也常常表现不佳。药物疗法，认知行为疗法和咨询只能缓解症状。几个候选基因显示参与多动症。最一致的是多巴胺受体4（DRD4）和溶质载体家族6成员3（SLC6A3）。我们分析了印加高加索人先证者中很少调查的DRD4和SLC6A3变异与ADHD核心性状的关联。ED，注意力不集中，组织效率和智商分别由Barkley Deficit在儿童和青少年执行功能量表，DSM-IV-TR，Conners父母评定量表和WISC中进行测量。通过PCR，RFLP，和/或基因组DNA的Sanger测序。DRD4变异主要影响注意力不集中，而SLC6A3变异显示与智商相关。很少有DRD4和SLC6A3变体与智商和注意力不集中相关。DRD4外显子3 VNTR> 4R对除智商以外的所有性状均表现出负面影响。注意力不集中与注意力跨度，组织效率和ED相关，而IQ则没有。我们推测，多巴胺能基因变异会影响ADHD的功能效率，智商和注意力可能会受到差异调节，因此应综合考虑这两个特征以提供更好的康复。4R对智商以外的所有性状均表现出负面影响。注意力不集中与注意力跨度，组织效率和ED相关，而IQ则没有。我们推断，多巴胺能基因变异会影响ADHD的功能效率，智商和注意力可能会受到差异调节，因此应综合考虑这两个特征以提供更好的康复。4R对智商以外的所有性状均表现出负面影响。注意力不集中与注意力跨度，组织效率和ED相关，而IQ则没有。我们推测，多巴胺能基因变异会影响ADHD的功能效率，智商和注意力可能会受到差异调节，因此应综合考虑这两个特征以提供更好的康复。