[Influence of ODD diagnosis on the association between NET1 and attention-deficit/hyperactivity disorder]

To explore the association between the SNP rs3785143 of NET1 gene and attention-deficit/hyperactivity disorder (ADHD) with and without oppositional defiant disorder (ODD).

Five hundreds and eighty-seven ADHD children with ODD, 1228 ADHD children without ODD and 554 healthy children were recruited from child psychiatric clinics of Peking University Sixth Hospital/Institute of Mental Health and included for genotyping of rs3785143. Comparisons of allelic and genotypic distribution among these groups were conducted.

In ADHD children with ODD, the genotypic distribution was significantly different from controls (P=0.008), showing higher TT frequency in ADHD with ODD (4.3% vs 1.6%, P=0.009). In ADHD children without ODD, the C allele (0.859 vs 0.821, P=0.005) and CC genotype (73.4% vs 65.9%, P=0.001) showed higher frequencies than controls. After controlling the potential influence of age and gender, those associations were retained. To further exclude the potential effect of other comorbidities, we repeated above analyses in pure ADHD and pure ADHD with ODD. In pure ADHD, the C allele (0.870 vs 0.821, P=0.003) and CC genotype (75.8% vs 65.9%, P=0.001) showed higher frequencies than controls; while in pure ADHD with ODD, the TT genotype showed higher frequency than controls (5.1% vs 1.6%, P=0.006).

We replicate the association between the SNP rs3785143 of NET1 gene and ADHD by case-control study.There may be different genetic mechanisms between ADHD with and without ODD.