Journal article

Absence of the 7-repeat variant of the DRD4 VNTR is associated with drifting sustained attention in children with ADHD but not in controls

Katherine A Johnson, Simon P Kelly, Ian H Robertson, Edwina Barry, Aisling Mulligan, Michael Daly, David Lambert, Caroline McDonnell, Thomas J Connor, Ziarih Hawi, Michael Gill, Mark A Bellgrove

American Journal of Medical Genetics Part B Neuropsychiatric Genetics | WILEY | Published : 2008


Many genetic studies have demonstrated an association between the 7-repeat (7r) allele of a 48-base pair variable number of tandem repeats (VNTR) in exon 3 of the DRD4 gene and the phenotype of attention deficit hyperactivity disorder (ADHD). Previous studies have shown inconsistent associations between the 7r allele and neurocognitive performance in children with ADHD. We investigated the performance of 128 children with and without ADHD on the Fixed and Random versions of the Sustained Attention to Response Task (SART). We employed time-series analyses of reaction-time data to allow a fine-grained analysis of reaction time variability, a candidate endophenotype for ADHD. Children were grou..

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Funding Acknowledgements

This work was supported by grants from the Health Research Board of Ireland, Science Foundation Ireland and the Irish Higher Education Authority's Programme for Research in Third-Level Institutions. KAJ is supported by the Health Research Board of Ireland. We would like to thank Dr. David Hevey for statistical advice, Aoife Daibhis, Amy Watchorn and Michelle Keavey for data collection, the referring child and adolescent psychiatrists from the Health Service Executive, South Western, Eastern and Midlands areas, the Lucena clinics, and all the participating children and their families.