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Open Access Research article

Association study of promoter polymorphisms at the dopamine transporter gene in Attention Deficit Hyperactivity Disorder

Xiaohui Xu1*, Jonathan Mill1, Bo Sun2, Chih-Ken Chen34, Yu-Shu Huang45, Yu-Yu Wu45 and Philip Asherson1

Author Affiliations

1 MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King's College London, UK

2 School of Medicine, King's College London, UK

3 Department of Psychiatry, Chang Gung Memorial Hospital, Taiwan

4 Chang Gung University School of Medicine, Taiwan

5 Department of Child Psychiatry, Chang Gung Children's Hospital, Taiwan

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BMC Psychiatry 2009, 9:3  doi:10.1186/1471-244X-9-3

Published: 5 February 2009

Abstract

Background

Attention deficit hyperactivity disorder (ADHD) is a complex neurobehavioral disorder. The dopamine transporter gene (DAT1/SLC6A3) has been considered a good candidate for ADHD. Most association studies with ADHD have investigated the 40-base-pair variable number of tandem repeat (VNTR) polymorphism in the 3'-untranslated region of DAT1. Only few studies have reported association between promoter polymorphisms of the gene and ADHD.

Methods

To investigate the association between the polymorphisms -67A/T (rs2975226) and -839C/T (rs2652511) in promoter region of DAT1 in ADHD, two samples of ADHD patients from the UK (n = 197) and Taiwan (n = 212) were genotyped, and analysed using within-family transmission disequilibrium test (TDT).

Results

A significant association was found between the T allele of promoter polymorphism -67A/T and ADHD in the Taiwanese population (P = 0.001). There was also evidence of preferential transmission of the T allele of -67A/T polymorphism in combined samples from the UK and Taiwan (P = 0.003). No association was detected between the -839C/T polymorphism and ADHD in either of the two populations.

Conclusion

The finding suggests that genetic variation in the promoter region of DAT1 may be a risk factor in the development of ADHD.