Meta-analysis Report
Basic Info
| Reference |
Smith TF, 201020468072
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| Citation |
Smith T. F. (2010) "Meta-analysis of the heterogeneity in association of DRD4 7-repeat allele and AD/HD: stronger association with AD/HD combined type." Am J Med Genet B Neuropsychiatr Genet, 153B(6): 1189-99.
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| Study Type |
Candidate association study |
| Summary |
The purpose of this meta-analysis was to examine whether association studies between attention deficit/hyperactivity disorder (AD/HD) and the dopamine receptor 4 gene 7-repeat (DRD4 7R) allele vary systematically based on study characteristics. A total of 27 empirical studies with 28 distinct samples using either case-control or family-based association analyses were included. Consistent with previous meta-analytic work [Gizer et al. (2009), Hum Genet 126:51-90], the DRD4 7R allele was associated with AD/HD across studies (OR=1.33; 95% CI=1.16-1.53, z=4.04, P-value=0.00005) and there was significant systematic variability among studies (Q=54.24; P-value=0.001; I2=50.22). To account for the variability among studies, sample and study level covariates were examined. No differences in overall effect size emerged between family-based and case-control studies. However, the risk allele frequency in the control population accounted for a significant portion of the variance in overall effect size within case-control studies. In addition, evidence for the association between the DRD4 7R allele and distinct AD/HD subtypes emerged across family-based and case-control studies. The proportion of AD/HD, combined type individuals within the AD/HD sample was associated with a significant increase in the magnitude of association between the DRD4 7R allele and AD/HD. Conversely, an increase in the proportion of AD/HD, predominantly inattentive type individuals within the AD/HD sample was associated with a decrease in study effect size. Implications regarding AD/HD etiological and phenotypic heterogeneity are discussed. |
Detail Info
| Samples |
A total of 27 studies and 28 samples were included in the overall meta-analysis. Sixteen case-control and 12 family-based samples were included. AD/HD was diagnosed according to DSM-IV criteria in the majority of studies. Some studies applied additional inclusion criteria. For more details, please refer to the article. |
| Statistic Method |
Meta-analysis of case-control, HHRR and TDT studies was conducted using Comprehensive Meta-Analysis (Version 2.0, BIOSTAT, Englewood, NJ) |
| Basic Result |
Consistent with previous meta-analytic work, the DRD4 7R allele was associated with AD/HD across studies and there was significant systematic variability among studies. In addition, evidence for the association between the DRD4 7R allele and distinct AD/HD subtypes emerged across family-based and case-control studies. The proportion of AD/HD, combined type individuals within the AD/HD sample was associated with a significant increase in the magnitude of association between the DRD4 7R allele and AD/HD. |
Genes reported by this study: 1
| Gene |
Statistical Values/Author Comments |
Result of Statistical Analysis |
| DRD4 |
consistent with previous meta-analytic work, the DRD4 7R all......
consistent with previous meta-analytic work, the DRD4 7R allele was associated with AD/HD across studies. Combined type individuals within the AD/HD sample was associated with a significant increase in the magnitude of association between the DRD4 7R allele and AD/HD.
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Significant
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