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	Ohadi M, 200616782077
Citation	Ohadi M., Shirazi E., Tehranidoosti M., Moghimi N., Keikhaee M. R., Ehssani S., Aghajani A. and Najmabadi H. (2006) "Attention-deficit/hyperactivity disorder (ADHD) association with the DAT1 core promoter -67 T allele." Brain Res, 1101(1): 1-4.
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	110 patients and 120 controls
Predominant Ethnicity	Iranian
Population	Iran
Gender	77 males and 33 females subjects, 80 males and 40 females controls
Age Group	Children/Adolescents : case: mean age 10 years (SD=5.0); control: 12 years (SD=4.0)

Detail Info

Summary	In this study, they examined whether either allele of the DAT1 core promoter -67 functional polymorphism is associated with ADHD in a case/control study. The allele and genotype frequencies of the polymorphism were studied in 110 patients and 120 controls, which were matched on the basis of sex, age and ethnicity. The genotype frequencies in the patients group were as follows: AA 19.2%; AT 65.2%; TT 15.4% vs. the genotype frequencies in the control group: AA 47.5%; AT 43.3%; TT 9.2%. The T allele of the -67A/T polymorphism revealed an ~1.56-fold excess in the patients group comparing with the controls. For the first time, these findings provide tentative evidence of the contribution of the DAT1 gene core promoter polymorphism to the etiopathophysiology of ADHD at least in the Iranian population that they have studied. Further work is warranted to confirm this finding and to assess its generalization to other ethnic groups.
Total Sample	110 unrelated Iranian subjects (77 males and 33 females) with ADHD were recruited for the study from the Child Psychiatry Clinic of the Rassool Akram Hospital-Iran Medical Sciences University and two private clinics in Tehran. One hundred and twenty unrelated Iranian normal children (80 males and 40 females) were randomly selected as controls. The two groups were matched on the basis of age, sex, and ethnic origin. The mean age of the patient and control groups was 10 (SD=5) years and 12 (SD=4) years, respectively.
Sample Collection	110 unrelated Iranian subjects with ADHD were recruited for the study from the Child Psychiatry Clinic of the Rassool Akram Hospital-Iran Medical Sciences University and two private clinics in Tehran. One hundred and twenty unrelated Iranian normal children were randomly selected as controls.
Diagnosis Description	All the patients in this study met the following criteria using Diagnostic and Statistical Manual of Mental Disorders (DSM-IV): six symptoms of inattention and/or hyperactivity/impulsiveness either in the home or school setting as determined by clinical interview; evidence of pervasiveness, defined as a minimum of four symptoms in the noncriterion setting; and onset before 7 years of age. The interviews were supplemented with the Conners Parent and Teacher Rating Scales (Conners, 1997) to assess the severity of disorder in each subject.
Technique	A 14 ml buccal sample was drawn from each subject. DNA was extracted using standard techniques and subsequently used as a template for the determination of DAT1 -67A/T alleles by polymerase chain reaction as described previously (Rubie et al., 2001).
Analysis Method	The Chi-square test was employed to compare frequency differences of the -67A/T alleles and genotypes between the groups studied. A P value of <=0.02 was considered significant, implementing the Bonferroni 0.5 mean correction to the conventional significant P value of <0.05.
Result Description	The genotype frequencies in the patients group were as follows: AA 19.2%; AT 65.2%; TT 15.4% vs. the genotype frequencies in the control group: AA 47.5%; AT 43.3%; TT 9.2% [X²=20.73, df=2, P<=0.0001]. The T allele of the -67A/T polymorphism revealed an ~1.56-fold excess in the patients group comparing with the controls [X²=14.50, df=1 (P<=0.001)]. For the first time, these findings provide tentative evidence of the contribution of the DAT1 gene core promoter polymorphism to the etiopathophysiology of ADHD at least in the Iranian population that they have studied.

Other variant reported by this study (count: 1)

Variant Name	Allele Change	Risk Allele	Statistical Values	Author Comments	Result of Statistical Analysis
SLC6A3 promoter -67A/T	A/T		chi-square test P-value<=0.0001, X²(1df)=14.50 fo...... chi-square test P-value<=0.0001, X²(1df)=14.50 for T allele; chi-square test genotypic P-value<=0.0001, X²(2df)=20.73 More...	significant association between the T allele and ADHD and a significant skew in the distribution of the genotypes was detected between the two groups	Significant

Genes reported by this study (count: 1)