Study Report

Basic Info
Reference |
Grevet EH, 200717690945
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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.
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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)
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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 |
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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...
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there were no significant alleles and genotypes differences in this case-control study |
Non-significant
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Genes reported by this study (count: 1)
Gene |
Statistical Values/Author Comments |
Result of Statistical Analysis |
SLC6A4 |
The 5-HTTLPR polymorphism was not associated with ADHD
The 5-HTTLPR polymorphism was not associated with ADHD
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Non-significant
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