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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	Aparecida da Silva M, 201120332413
Citation	Aparecida da Silva M., Cordeiro Q., Louza M. and Vallada H. (2011) "Lack of association between a 3'UTR VNTR polymorphism of dopamine transporter gene (SLC6A3) and ADHD in a Brazilian sample of adult patients." J Atten Disord, 15(4): 305-9.
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	102 cases and 479 controls
Predominant Ethnicity	Brazilian
Population	Brazil
Gender	61.20% male in case sample, 67.15% male in control group
Age Group	Adults : aged 18-60 years, mean age 33.0 years (SD=9.21) for case group, mean age 32.5 years (SD=9.5) for control group

Detail Info

Summary	To investigate a possible association between a 3'UTR VNTR polymorphism of the dopamine transporter gene (SLC6A3) and ADHD in a Brazilian sample of adult patients. They studied Case-control with 102 ADHD adult outpatients (DSM-IV criteria) and 479 healthy controls. Alleles of the 3' UTR were coded according to their number of repeats: 6-repeat 320 bp (allele 6), 8-repeat 400 bp (allele 8), 9-repeat 440 bp (allele 9), 10-repeat 480 bp (allele 10), and 11-repeat 520 bp (allele 11). There were no allelic (X²=2.67, 5 df, p=0.75) and genotypic (X²=7.20, 1 df, p=0.61) association between adult ADHD and VNTR 3'UTR polymorphism of SLC6A3. These findings do not support SLC6A3 as marker genetic susceptibility factor in adult ADHD. More comprehensive polymorphism coverage within the SLC6A3 region should be conducted in larger samples, including comparisons in clinical subgroups, and in samples with different ethnic backgrounds.
Total Sample	The total sample consisted of 102 cases and 479 controls. Among the 102 ADHD patients, 61.20% were men and 38.30% were women, whereas in the control group, 67.15% were men and 32.85% were women. The mean ages of the ADHD and control groups were 33.0 (SD=9.21) and 32.5 (SD=9.5) respectively. More information about the clinical sample may be found elsewhere (Silva et al., 2006).
Sample Collection	All patients were recruited from an ADHD adult outpatient unit (PRODATH) at the Institute of Psychiatry of Sao Paulo University Medical School. The control group was consisted of 479 selected individuals from consecutively unrelated men and women admitted to the Blood Donation Center at the Sao Paulo University Medical School. Individuals were submitted to a nonstructured interview about psychiatric condition. The control group was matched by gender and age. This study was approved by the University Hospital ethics committee. Written informed consent was obtained from all participating participants.
Diagnosis Description	The diagnosis of the ADHD patients was made according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV) criteria by two independent senior psychiatrists with expertise in ADHD. Only patients between 18 and 60 years of age who fulfilled criteria for ADHD during childhood and at present were included. The criteria for exclusion were previous evidence of neurological illness, psychosis, or mental retardation.
Technique	Genomic DNA was obtained from venous blood from each participant. The DAT1 VNTR polymorphisms were amplified in a hot-start protocol involving an initial 5-min denaturing step at 95^oC, followed by 35 cycles of 95^oC for 45 sec, 60^oC for 45 sec, 72^oC for 45 sec, and 72^oC for 6 min. For the DAT1 3'UTR polymorphism, the primers' sequence used was: 3'UTR-Forward: 5' TGT GGT GAT GGG AAC GGC CTG AG 3' and 3'UTR-Reverse: 5' CTT CCT GGA GGT CAC GGC TCA AGG 3'. The products were electrophoresed on 3% de agarose gel. Alleles of the 3'UTR were coded according to the number of repeats they contain: 6-repeat 320 bp (allele 6), 8-repeat 400 bp (allele 8), 9-repeat 440 bp (allele 9), 10-repeat 480 bp (allele 10) and 11-repeat 520 bp (allele 11).
Analysis Method	The statistical power of the sample was evaluated using the CaTS Program (Center for Statistical Genetics--The University of Michigan). Genotype and allele frequencies were compared using a X² test, and p values were investigated by the Monte Carlo method using the Clump v1.9 with 10,000 simulations. The Hardy-Weinberg equilibrium (HWE) test was performed by the HWE program.
Result Description	The genotypic distribution was in HWE (cases: X²=21.01, p=0.13 and controls: ¦Ö²=1.45, p=0.99). The power of the sample, based on 102 patients and 479 controls, ADHD prevalence in adults of 5%, average allelic frequency around 70%, multiplicative model with the genotype relative risk of 1.6, and significance level of 0.05, was 80%. There were no allelic (¦Ö²=2.67, 5df, p=0.75) and genotypic (¦Ö²=7.20, 9df, p=0.61) association between adult ADHD and VNTR 3'UTR polymorphism.

Other variant reported by this study (count: 1)

Variant Name	Allele Change	Risk Allele	Statistical Values	Author Comments	Result of Statistical Analysis
SLC6A3 3'-UTR VNTR	4, 7-11 repeat		allelic chi-square test P-value=0.75 (5df); genotypic chi-sq...... allelic chi-square test P-value=0.75 (5df); genotypic chi-square test P-value=0.61 (9df) More...	There is no association between adult ADHD and VNTR 3'UTR polymorphism	Non-significant

Genes reported by this study (count: 1)