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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

Study Report

Basic Info

Reference	Bellgrove MA, 200515654584
Citation	Bellgrove M. A., Domschke K., Hawi Z., Kirley A., Mullins C., Robertson I. H. and Gill M. (2005) "The methionine allele of the COMT polymorphism impairs prefrontal cognition in children and adolescents with ADHD." Exp Brain Res, 163(3): 352-60.
Study Design	case-control and family-based
Study Type	Candidate-gene association study
Sample Size	179 cases and their parents
Predominant Ethnicity	Caucasian
Population	Ireland
Age Group	Children/Adolescents : 4-16 years

Detail Info

Summary	Here they tested for association of this polymorphism with ADHD and examined its influence on prefrontal cognition in ADHD. They re-examined the previous finding of an association between the Val158Met COMT gene polymorphism and ADHD with an extended sample of 179 ADHD cases using a family control design. They also examined the performance of children and adolescents with ADHD (n=61) on a standardised test of sustained attention. Analysis confirmed the absence of an association between the Val158Met COMT gene polymorphism and the clinical phenotype of ADHD. COMT genotype, however, affected prefrontal cognition in ADHD. Children possessing the methionine variant performed significantly below agerelated norms on tests of sustained attention. Contrary to expectations, the methionine variant of the Val158- Met COMT gene polymorphism impaired prefrontally mediated cognition in ADHD.
Total Sample	In this study, they extended the original sample to 179 cases with ADHD and their respective parents, aged 4-16 years.
Sample Collection	details about sample collection, please refer to Kirley et al. 2002
Diagnosis Description	Diagnoses were made according to DSM-IV criteria. Further details of the assessment and diagnosis can be found in (Kirley et al. 2002).
Technique	DNA was extracted from whole blood using the standard phenol chloroform procedure. PCR amplification conditions, cycling and genotyping were as described elsewhere (Domschke et al. 2004).
Analysis Method	Transmission Disequilibrium Test was used to examine any association between the Val158 Met COMT polymorphism and ADHD.
Result Description	Analysis confirmed the absence of an association between the Val158Met COMT gene polymorphism and the clinical phenotype of ADHD. COMT genotype, however, affected prefrontal cognition in ADHD: ADHD children who were homozygous for the valine variant had significantly better sustained attention than those ADHD children possessing at least one copy of the methionine variant. Children possessing the methionine variant performed significantly below agerelated norms on tests of sustained attention. Contrary to expectations, the methionine variant of the Val158- Met COMT gene polymorphism impaired prefrontallymediated cognition in ADHD.

SNPs reported by this study (count: 1)

Genes reported by this study (count: 1)