Study Report

Basic Info
Reference |
Kirley A, 200415389763
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Citation |
Kirley A., Lowe N., Mullins C., McCarron M., Daly G., Waldman I., Fitzgerald M., Gill M. and Hawi Z. (2004) "Phenotype studies of the DRD4 gene polymorphisms in ADHD: association with oppositional defiant disorder and positive family history." Am J Med Genet B Neuropsychiatr Genet, 131B(1): 38-42.
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Study Design |
family-based |
Study Type |
Candidate-gene association study |
Sample Size |
178 families |
Predominant Ethnicity |
Caucasian |
Population |
Ireland |
Age Group |
Children/Adolescents
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Detail Info
Summary |
The objective of this study was to investigate association of DRD4 polymorphisms with ADHD subtypes for which there is evidence for increased heritability. The genetic variants tested were the 120 bp insertion/deletion, the -616, -521, -376, and the 48 bp DRD4 VNTR. The primary analyses were of association with oppositional defiant disorder (ODD), conduct disorder (CD), and diagnostic subtypes. Secondary analyses of clinical subtype were exploratory in nature and included analysis of association of DRD4 polymorphisms with family history of ADHD. They observed significant association between DRD4 7-repeat allele transmission and ADHD children with comorbid ODD. The DRD4 7-repeat allele was also significantly associated with family history positive ADHD. They observed no significant distortion in the transmission of any of the tested DRD4 variants with inattentive or hyperactive-impulsive subtypes or symptom dimensions. |
Total Sample |
One hundred and seventy eight children and their families took part in the study. |
Sample Collection |
178 families with clinically diagnosed ADHD children were recruited from child guidance clinics and ADHD support groups around Ireland |
Diagnosis Description |
To confirm DSM-IV and/or ICD-10 diagnoses of ADHD, one or both parents of each child were interviewed using the child and adolescent psychiatric assessment (CAPA) [Angold et al., 1995]. With regard to DSM-IV ADHD, 112 children (62.9%) met research criteria for ADHD combined type, 21 (11.8%) for ADHD inattentive type, and 11 (6.1%) for ADHD hyperactiveimpulsive type. |
Technique |
PCR amplification and genotyping methods for DRD4 markers is described in the accompanying paper by Lowe et al. |
Analysis Method |
Exploratory analyses were performed using a Logistic Regression based extension of the TDT (LRTDT) [Waldman et al., 1999]. |
Result Description |
They observed significant association between DRD4 7-repeat allele transmission and ADHD children with comorbid ODD (chi(2)=6.74, df=1, P=0.01, OR=2.45) The DRD4 7-repeat allele was also significantly associated with family history positive ADHD (chi(2)=10.12, df=1, P=0.0021, OR=3.57). They observed no significant distortion in the transmission of any of the tested DRD4 variants with inattentive or hyperactive-impulsive subtypes or symptom dimensions. |

Other variant reported by this study (count: 5)
Variant Name |
Allele Change |
Risk Allele |
Statistical Values |
Author Comments |
Result of Statistical Analysis |
DRD4 promoter duplication 120bp |
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allelic TDT P-value=1.0, X2=0.02 in combined subt......
allelic TDT P-value=1.0, X2=0.02 in combined subtype
More...
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there was no association between this variant and DSM-IV combined type ADHD |
Non-significant
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DRD4 promoter -376C/T |
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allelic TDT P-value=1.0, X2=0 in combined subtype
allelic TDT P-value=1.0, X2=0 in combined subtype
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there was no association between this variant and DSM-IV combined type ADHD |
Non-significant
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DRD4 exon3 VNTR |
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7R |
allelic TDT P-value=0.198, X2=1.94 in all proband......
allelic TDT P-value=0.198, X2=1.94 in all probands, TDT P-value=0.098, X2=3.19 in combined subtype
More...
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there was no association of the DRD4 7-repeat allele in all probands and combined subtype |
Non-significant
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DRD4 promoter -616C/G |
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allelic TDT P-value=0.21, X2=1.86 in combined sub......
allelic TDT P-value=0.21, X2=1.86 in combined subtype
More...
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there was no association between this variant and DSM-IV combined type ADHD |
Non-significant
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DRD4 promoter -521C/T |
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allelic TDT P-value=0.33, X2=1.13 in combined sub......
allelic TDT P-value=0.33, X2=1.13 in combined subtype
More...
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there was no association between this variant and DSM-IV combined type ADHD |
Non-significant
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Genes reported by this study (count: 1)
Gene |
Statistical Values/Author Comments |
Result of Statistical Analysis |
DRD4 |
there was no association between the investigated variants a......
there was no association between the investigated variants and ADHD
More...
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Non-significant
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