1. ¹Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, London, UK
2. ²Department of Psychiatry, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Ireland
3. ³Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
4. ⁴Department of Psychiatry, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
5. ⁵ADHD Clinic, Geha Mental Health Center, Petak Tikvah, Israel
6. ⁶Triversum, Alkmaar, Holland
7. ⁷Amsterdam Medical Centre de Bascule, Amsterdam, Holland
8. ⁸University Clinic for Child and Adolescent Psychiatry, Essen, Germany
9. ⁹Child and Adolescent Psychiatry, University of Göttingen, Göttingen, Germany
10. ¹⁰Department of Experimental Clinical Health Psychology, Ghent University, Ghent, Belgium
11. ¹¹Shaare Zedek Medical Center, Jerusalem, Israel
12. ¹²Department of Developmental and Educational Psychology, University of Valencia, Valencia, Spain
13. ¹³University Centre for Child and Adolescence Psychiatry, University Medical Centre, Groningen, The Netherlands
14. ¹⁴Department of Child and Adolescent Psychiatry, University of Zurich, Zurich, Switzerland
15. ¹⁵Vrije Universiteit, Amsterdam, Holland
16. ¹⁶School of Psychology, University of Southampton, Highfield, Southampton, UK
17. ¹⁷Department of Psychiatry and Neuroscience and Physiology, SUNY Upstate Medical University, Syracuse, NY, USA

Correspondence: Professor P Asherson, Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, UK. E-mail: p.asherson@iop.kcl.ac.uk

¹⁸Shared first authorship.

Received 25 June 2007; Revised 7 September 2007; Accepted 18 September 2007; Published online 8 January 2008.

Abstract

As part of the International Multi-centre ADHD Genetics project we completed an affected sibling pair study of 142 narrowly defined Diagnostic and Statistical Manual of Mental Disorders, fourth edition combined type attention deficit hyperactivity disorder (ADHD) proband–sibling pairs. No linkage was observed on the most established ADHD-linked genomic regions of 5p and 17p. We found suggestive linkage signals on chromosomes 9 and 16, respectively, with the highest multipoint nonparametric linkage signal on chromosome 16q23 at 99 cM (log of the odds, LOD=3.1) overlapping data published from the previous UCLA (University of California, Los Angeles) (LOD>1, 95 cM) and Dutch (LOD>1, 100 cM) studies. The second highest peak in this study was on chromosome 9q22 at 90 cM (LOD=2.13); both the previous UCLA and German studies also found some evidence of linkage at almost the same location (UCLA LOD=1.45 at 93 cM; German LOD=0.68 at 100 cM). The overlap of these two main peaks with previous findings suggests that loci linked to ADHD may lie within these regions. Meta-analysis or reanalysis of the raw data of all the available ADHD linkage scan data may help to clarify whether these represent true linked loci.