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Confirmation that a specific haplotype of the dopamine transporter gene is associated with combined-type ADHD
Philip Asherson1, Keeley Brookes, Barbara Franke
1MRC Social Genetic Developmental and Psychiatry Centre, Institute of Psychiatry, London, SE5 8AF UK. p.asherson@iop.kcl.ac.uk
Objective:
The primary purpose of this study was to confirm the association of a specific haplotype of the dopamine transporter gene and attention deficit hyperactivity disorder (ADHD), which could be one source of the heterogeneity seen across published studies.
Method:
The authors previously reported the association of ADHD with a subgroup of chromosomes containing specific alleles of two variable-number tandem repeat polymorphisms within the 3' untranslated region and intron 8 of the dopamine transporter gene. They now report on this association in a sample of ADHD combined-type probands.
Results:
The original observations were confirmed, with an overall odds ratio of 1.4 across samples.
Conclusions:
These data challenge results of meta-analyses suggesting that dopamine transporter variation does not have an effect on the risk for ADHD, and they indicate that further investigation of functional variation in the gene is required.
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