The genetics of attention-deficit/hyperactivity disorder

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder that almost certainly represents the common outcome of multiple causal pathways and it is now generally accepted that genetic factors make a significant contribution to these pathways. Behavioral studies suggest a heritability of approximately 0.76. While molecular genetic approaches have identified a range of potential candidate genes, it is now clear that the genetics of ADHD are characterized by a number of genes each of which makes a small but significant contribution to the overall risk. Several genome-wide linkage studies have been conducted and, although there are considerable differences in findings between studies, several regions have been supported across several studies (bin 16.4, 5p13, 11q22–25, 17p11). The contribution of several candidate genes has been supported by meta-analyses (DRD4, DRD5, DAT1, HTR1B and SNAP25). Genome-wide association scans are starting to appear but have not yet had sufficient power to produce conclusive results. Gene–environment interactions, which are as yet relatively understudied, are likely to be of importance in fully understanding the role of genes in ADHD and will be discussed.

Keywords::

• association study
• attention-deficit/hyperactivity disorder
• candidate gene
• dopamine
• etiology
• genetic marker
• genetics
• linkage disequilibrium
• linkage studies
• neurotrophin
• noradrenaline
• serotonin

Financial & competing interests disclosure

David Coghill’s department has had research support from Lilly, Janssen Cilag and Shire. He has served in an advisory or consultancy role for Lilly, Janssen Cilag, Pfizer, Shire, Flynn and UCB. He received conference attendance support or was paid for public speaking by Lilly, Janssen McNeil and UCB. Tobias Banaschewski served in an advisory or consultancy role for Lilly, Medice, Novartis, Pfizer, Shire and UCB. He received conference attendance support or was paid for public speaking by Lilly, Janssen McNeil, Medice, Novartis and UCB. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.