Gene for the serotonin transporter and ADHD: no association with two functional polymorphisms
Karen G Wigg1, Amandeep Takhar, Abel Ickowicz
1Department of Psychiatry, Cell and Molecular Division, The Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada.
Summary
This study investigated the serotonin transporter gene (HTT) and its association with attention-deficit hyperactivity disorder (ADHD). No significant genetic associations were found between HTT polymorphisms and ADHD in the studied families.
Area of Science:
- Neuroscience
- Genetics
- Psychiatry
Background:
- The serotonergic system is implicated in attention-deficit hyperactivity disorder (ADHD) development.
- The serotonin transporter (HTT) gene, regulating serotonin levels, has been previously associated with ADHD, particularly its long promoter variant.
- A recent single nucleotide polymorphism (SNP) within the HTT promoter may have confounded prior association studies.
Purpose of the Study:
- To investigate the relationship between multiple serotonin transporter gene (HTT) variants and ADHD.
- To examine promoter polymorphisms, a 3' untranslated region (3'UTR) SNP, and a rare coding SNP for ADHD association.
- To analyze the combined effect of these polymorphisms through haplotype analysis.
Main Methods:
- Genotyping of 209 families with attention-deficit hyperactivity disorder (ADHD) probands.
- Analysis of specific HTT polymorphisms: promoter insertion/deletion, 3'UTR SNP, and a non-synonymous coding SNP.
- Haplotype analysis to assess combined effects of linked polymorphisms.
Main Results:
- No statistically significant association was found between the examined serotonin transporter gene (HTT) polymorphisms and attention-deficit hyperactivity disorder (ADHD).
- Haplotype analysis also did not reveal any significant association with ADHD in this cohort.
- The findings do not support a role for these specific HTT variants in ADHD susceptibility in the studied population.
Conclusions:
- This study did not find evidence supporting an association between the investigated serotonin transporter gene (HTT) variants and attention-deficit hyperactivity disorder (ADHD).
- The results suggest that these specific HTT polymorphisms may not be major genetic contributors to ADHD in the studied sample.
- Further research with larger and diverse cohorts may be necessary to fully elucidate the complex genetic underpinnings of ADHD.
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