ADHDgene Database

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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	Kissling C, 200817948273
Citation	Kissling C., Retz W., Wiemann S., Coogan A. N., Clement R. M., Hunnerkopf R., Conner A. C., Freitag C. M., Rosler M. and Thome J. (2008) "A polymorphism at the 3'-untranslated region of the CLOCK gene is associated with adult attention-deficit hyperactivity disorder." Am J Med Genet B Neuropsychiatr Genet, 147(3): 333-8.
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	143 unrelated male adults
Predominant Ethnicity	Caucasian
Population	Germany
Gender	all are males
Age Group	Adults : mean age 31.3,SD=11.7 (SD)

Detail Info

Summary	This study compared self-rating and interview based measures of ADHD psychopathology of 143 subjects with and without ADHD with their rs1801260 genotype to test the hypothesis that ADHD is linked to one of the alleles of the CLOCK polymorphism. The T>C single nucleotide polymorphism rs1801260 was genotyped in DNA isolated from blood samples. The associations between genotype and ADHD scores were compared using non-parametric ANCOVA with post hoc pairwise comparisons. There was a strong, significant association (P-value<0.001) between each of the adult ADHD assessments and the rs1801260 polymorphism with at least one T-mutation being the risk allele. This is the first study suggesting that a polymorphism of a gene within the circadian 'clock' mechanism is a direct or linked contributing factor in adult ADHD.
Total Sample	The study enrolled 143 male adults, consecutively referred for psychiatric examination to the Institute of Forensic Psychiatry of the Saarland University. Average age was 31.3,SD=11.7.
Sample Collection	Caucasians of western European origin and German background
Diagnosis Description	ADHD symptoms were assessed according to their relative ADHD-scores following self-report scales, the Wender-Reimherr diagnostic interview and validated background data. Comorbid disorders were diagnosed according to DSM-IV and ICD-10 criteria, using modified, standardized checklists as reported by Rosler et al. No subjects with a diagnosis of current substance dependence, acute schizophrenia, major depression/ bipolar disorder, or any other severe Axis-I diagnosis according to DSM-IV as well as subjects with the diagnosis of mental retardation (IQ<70) were admitted to participate to the study.
Technique	Genomic DNA was extracted from 10 ml whole blood of each subject using the commercial Invisorb1 Blood Giga Kit (Invitek, Berlin, Germany) and concentration was adjusted using a PicoGreen fluorometric assay (Molecular Probes/Invitrogen, Paisley, United Kingdom). For more details, please refer to the original publication.
Analysis Method	Allele frequencies of the group were calculated by direct counting from the genotypes observed and tested for Hardy-Weinberg equilibrium (HWE), using a Chi-squared test between observed and expected values. Descriptive data between genotypes were compared by non-parametric analysis of variance (ANOVA) or w²-tests. Possible confounding variables (criterion P-value<0.10) associated with a specific genotype were controlled for in further analyses.
Result Description	There was a strong, significant association between each of the adult ADHD assessments and the rs1801260 polymorphism with at least one T-mutation being the risk allele.

SNPs reported by this study (count: 1)

Genes reported by this study (count: 1)