Candidate system analysis in ADHD: Evaluation of nine genes involved in dopaminergic neurotransmission identifies association with DRD1

Abstract

Objectives. Several pharmacological and genetic studies support the involvement of the dopamine neurotransmitter system in the aetiology of attention-deficit hyperactivity disorder (ADHD). Based on this information we evaluated the contribution to ADHD of nine genes involved in dopaminergic neurotransmission (DRD1, DRD2, DRD3, DRD4, DRD5, DAT1, TH, DBH and COMT). Methods. We genotyped a total of 61 tagging single nucleotide polymorphisms (SNPs) in a sample of 533 ADHD patients (322 children and 211 adults), 533 sex-matched unrelated controls and additional 196 nuclear ADHD families from Spain. Results. The single- and multiple-marker analysis in both population and family-based approaches provided preliminary evidence for the contribution of DRD1 to combined-type ADHD in children (P = 8.8e-04; OR = 1.50 (1.18–1.90) and P = 0.0061; OR = 1.73 (1.23–2.45)) but not in adults. Subsequently, we tested positive results for replication in an independent sample of 353 German families with combined-type ADHD children and replicated the initial association between DRD1 and childhood ADHD (P = 8.4e-05; OR = 3.67 (2.04–6.63)). Conclusions: The replication of the association between DRD1 and ADHD in two European cohorts highlights the validity of our finding and supports the involvement of DRD1 in childhood ADHD.

Key words::

• Genetics
• biological psychiatry
• childhood ADHD
• DRD1
• association study

Acknowledgements

We are grateful to all children and parents for their participation in the study and to M. Dolors Castellar and A. Daví for their help in the recruitment of control subjects. N. Steigerwald and N. Dörung are credited for excellent technical assistance. Financial support was received from “Instituto de Salud Carlos III-FIS” (PI041267, PI042010, PI040524 and PI080519), “Fundació La Marató de TV3” (ref. 092330/31), “Agència de Gestió d'Ajuts Univ ersitaris i de Recerca-AGAUR” (2009SGR971), DFG (Grant RE1632/1-5 to AR, KFO 125 to AR and KPL; SFB TRR 58 to AR and KPL; ME 1923/5-1, ME 1923/5-3 to JM and CF, GRK 1389 to JM) and BMBF (IZKF Würzburg N-27-N, to AR; 01GV0605, to KPL). MR is a recipient of a Miguel de Servet contract from the “Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación”, Spain

Statement of Interest

None to declare.