Molecular genetic studies in attention deficit hyperactivity disorder (ADHD) have focussed on candidate genes within the dopamine system, which is thought to be the main site of action of stimulant drugs, the primary pharmacological treatment of the disorder. 1 Of particular interest are findings with the dopamine transporter gene (DAT1), since stimulant drugs interact directly with the transporter protein.2,3 To date, there have been eight published association studies of ADHD with a 480 basepair allele of a variable number tandem repeat (VNTR) polymorphism in the 3Ј-untranslated region of the gene, five 4-8 that support an association and three 9-11 against. We have analysed the same VNTR marker in a dataset of UK Caucasian children and an independent dataset of Turkish Caucasian children with DSM-IV ADHD, using the transmission disequilibrium test (TDT).12 Results from the UK ( In this study, we have taken a family-based association design to investigate the DAT1 VNTR marker in a dataset of UK Caucasian children and an independent dataset of Turkish Caucasian children. Cases were included if they had a diagnosis of ADHD under DSM-IV criteria and DNA from both parents available for genotyping. They were excluded if they had neurological disease or damage or congenital disorders known to cause hyperactivity. The UK sample consisted of 59 cases with the combined subtype, six the hyperactive/impulsive subtype and one the inattentive subtype of ADHD. Axis 1 co-morbidity other than oppositional defiant disorder and conduct disorder (ODD/CD) consisted of two cases with an affective disorder. The Turkish sample consisted of 111 complete trios with DSM-IV-ADHD combined type. Comorbid diagnoses other than ODD/CD were Tourette's syndrome and/or tics (TS/tics) in 34% and anxiety/depression in 8% of probands.Analysis was performed using the transmission disequilibrium test (TDT) of linkage in the presence of association.12 In order to further evaluate the evidence, we included data from other published reports and performed a combined analysis. The results of this study are shown in Table 1. When considered alone, data from the UK sample ( 2 = 6.12, P = 0.0.01, OR = 1.95), but not the Turkish sample ( 2 = 0.93, P = 0.335), support association and linkage between the DAT1 locus and ADHD.We are not alone in finding differences between datasets. Among previous published reports there have been five providing evidence for the association and three against. The reasons for this are unclear and require further investigation, but may relate to the statistical power of individual samples. To address this issue we combined available published data on the VNTR polymorphism and applied the TDT. Because the TDT is primarily a test of linkage, it is valid to analyse the combined data by adding the number of transmitted and non-transmitted alleles across different studies. As shown in Table 1, combined analysis provides evidence for association and linkage at an alphalevel of 0.06 and odds ratio of 1.15. Although diagnostic differences...

Early post-disaster intervention addressing children and their educational milieu provides children with significant symptomatic reduction, allowing the mobilization of adaptive coping, thereby enhancing their overall functioning as observed in school.

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