ADHDgene Database

Hot Results

Quick Search

Keyword:
Type:

Large-scale studies

Data Summary

Published Variant
- SNP: 1391
- CNV: 398
- Others: 173
Published Gene: 359
Published Region: 128
Pathway by PBA: 8
Study: 361

Meta-analysis Report

Basic Info

Reference	Ouakil DP, 200515722958
Citation	Purper-Ouakil D., Wohl M., Mouren M. C., Verpillat P., Ades J. and Gorwood P. (2005) "Meta-analysis of family-based association studies between the dopamine transporter gene and attention deficit hyperactivity disorder." Psychiatr Genet, 15(1): 53-9.
Study Type	Candidate association study
Summary	With an equal number of positive and negative association studies between the 10-repeat of the DAT gene and ADHD, a meta-analysis is required for this other candidate gene. They re-analysed the 13 published family-based association studies between ADHD and the DAT gene. Following recent recommendations, different biases were specifically assessed, such as the sample-size effect and the time effect. The meta-analysis showed no significant association between ADHD and the DAT gene, but an important between-samples heterogeneity. Odds ratios above 1 are mostly observed in studies with a small number of informative transmissions, and decrease with larger sample size. Contrary to what was found for the DRD4 gene, the 10-repeat allele of the DAT gene has at most a minor role in the genetic susceptibility of ADHD. The different biases detected herein probably explain the initial impression of a significant impact of the DAT gene on hyperactivity.

Detail Info

Samples	Association studies between ADHD and the 10-repeat allele of the DAT gene were detected through the National Library of Medicine (NLM) MEDLINEs and Currents Contents databases. Reference lists of all articles were scanned to identify missed articles. The databases were searched up to February 2004 and did not include abstracts presented but not published. Articles with subgroups already published were carefully searched and excluded. Among the 12 published studies, 11 papers gave information for a TDT. They did not include Roman et al. (2001) because the authors published a Haplotype Relative Risk (HRR) analysis without the number of transmissions from heterozygous parents. The 12 published studies using a TDT described 13 independent samples, which represented 885 transmissions.
Statistic Method	They combined data from studies for which sufficient data were included to conduct a TDT. The Woolf method (Woolf, 1955) allows the calculation of total X², gives a X² estimating the between-samples heterogeneity, and evaluates the specific X² value. As the studies analysed here are family-based, they used a McNemar chi-square to evaluate (or re-evaluate) each result, even if different methods were presented in the published article. The odds ratios of the published studies were analysed according to the time effect and the sample size effect in order to detect two biases. The sample size effect was measured on the basis of number of transmitted alleles. Non-parametric correlation tests were used to test the relationship between months after publications and number of transmitted alleles on the one hand, and the computed odds ratio of each sample on the other.
Basic Result	The meta-analysis showed no significant association between ADHD and the DAT gene (P=0.21), but an important between-samples heterogeneity (P=0.0009). Odds ratios above 1 are mostly observed in studies with a small number of informative transmissions, and decrease with larger sample size.

Genes reported by this study: 1