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	Grevet EH, 200717690945
Citation	Grevet E. H., Marques F. Z., Salgado C. A., Fischer A. G., Kalil K. L., Victor M. M., Garcia C. R., Sousa N. O., Belmonte-de-Abreu P. and Bau C. H. (2007) "Serotonin transporter gene polymorphism and the phenotypic heterogeneity of adult ADHD." J Neural Transm, 114(12): 1631-6.
Study Design	case-control
Study Type	Candidate-gene association study
Sample Size	312 adult patients and 236 controls
Predominant Ethnicity	Caucasian
Population	Brazil
Gender	166 (53%) male and 146 (47%) female patients
Age Group	Adults : mean age 34.1 years (SD=11.1)

Detail Info

Summary	The present study investigates possible associations between the 5-HTT control region polymorphism (5-HTTLPR) with adult ADHD, including subtypes, severity, temperament profile and comorbidities. The polymorphic site was genotyped in 312 adult patients with ADHD and 236 controls, all of them Brazilians of European descent. The interviews followed the DSM-IV criteria, using the K-SADS-E for ADHD and oppositional defiant disorder, SCID-I and MINI for comorbidities and the TCI for temperament dimensions. The 5-HTTLPR polymorphism was not associated with ADHD. Carriers of the S allele presented slightly higher inattention and novelty seeking scores, and a higher frequency of drug dependence. These differences do not persist after correction for multiple comparisons. These results suggest that the 5-HTTLPR polymorphism does not have a direct role in the predisposition to adult ADHD. There is suggestive evidence for a small effect in some behavioral phenotypes related to ADHD.
Total Sample	Three hundred and twelve adult ADHD patients of European descent comprised the sample. The control group for allele and genotype frequencies is composed of 236 European Brazilian blood donor males assessed in a blood bank.
Sample Collection	The patients were evaluated in the adult ADHD outpatient clinic of the Clinical Hospital of Porto Alegre (a major teaching hospital) from September 2002 to December 2005. The control group for allele and genotype frequencies is composed of 236 European Brazilian blood donor males assessed in a blood bank.
Diagnosis Description	The interviews followed the DSM-IV criteria, using the K-SADS-E for ADHD and oppositional defiant disorder, SCID-I and MINI for comorbidities and the TCI for temperament dimensions.
Technique	The DNA was extracted (Lahiri and Nurnberger 1991), and the polymorphic region 5-HTTLPR was amplified using the polymerase chain reaction (PCR) adapted from Seeger et al. (2001) and Manor et al. (2001).
Analysis Method	Allele frequencies were estimated by gene counting. The genotype and allele frequency comparisons between ADHD patients (including subgroups) and controls were performed with the Chi-square test. Significance level was set at P<0.001 after Bonferroni correction considering all tests performed.
Result Description	The 5-HTTLPR polymorphism was not associated with ADHD. Carriers of the S allele presented slightly higher inattention and novelty seeking scores, and a higher frequency of drug dependence. These differences do not persist after correction for multiple comparisons. These results suggest that the 5-HTTLPR polymorphism does not have a direct role in the predisposition to adult ADHD. There is suggestive evidence for a small effect in some behavioral phenotypes related to ADHD.

Other variant reported by this study (count: 1)

Variant Name	Allele Change	Risk Allele	Statistical Values	Author Comments	Result of Statistical Analysis
5HTTLPR	short/long		chi-square test P-value=0.95, X²=0.69 for genotyp...... chi-square test P-value=0.95, X²=0.69 for genotype frequency, chi-square test P-value=0.34, X²=0.92 for allele frequency between ADHD and controls, chi-square test P-value=0.69, X²=1.47 for allele frequency between inattentives&combined and controls More...	there were no significant alleles and genotypes differences in this case-control study	Non-significant

Genes reported by this study (count: 1)