Genetics and epigenetics in major psychiatric disorders: dilemmas, achievements, applications, and future scope
Language: 
English
Short Title: 
Genetics and epigenetics in major psychiatric disorders
Abstract: 

No specific gene has been identified for any major psychiatric disorder, including schizophrenia, in spite of strong evidence supporting a genetic basis for these complex and devastating disorders. There are several likely reasons for this failure, ranging from poor study design with low statistical power to genetic mechanisms such as polygenic inheritance, epigenetic interactions, and pleiotropy. Most study designs currently in use are inadequate to uncover these mechanisms. However, to date, genetic studies have provided some valuable insight into the causes and potential therapies for psychiatric disorders. There is a growing body of evidence suggesting that the understanding of the genetic etiology of psychiatric illnesses, including schizophrenia, will be more successful with integrative approaches considering both genetic and epigenetic factors. For example, several genes including those encoding dopamine receptors (DRD2, DRD3, and DRD4), serotonin receptor 2A (HTR2A) and catechol-O-methyltransferase (COMT) have been implicated in the etiology of schizophrenia and related disorders through meta-analyses and large, multicenter studies. There is also growing evidence for the role of DRD1, NMDA receptor genes (GRIN1, GRIN2A, GRIN2B), brain-derived neurotrophic factor (BDNF), and dopamine transporter (SLC6A3) in both schizophrenia and bipolar disorder. Recent studies have indicated that epigenetic modification of reelin (RELN), BDNF, and the DRD2 promoters confer susceptibility to clinical psychiatric conditions. Pharmacologic therapy of psychiatric disorders will likely be more effective once the molecular pathogenesis is known. For example, the hypoactive alleles of DRD2 and the hyperactive alleles of COMT, which degrade the dopamine in the synaptic cleft, are associated with schizophrenia. It is likely that insufficient dopaminergic transmission in the frontal lobe plays a role in the development of negative symptoms associated with this disorder. Antipsychotic therapies with a partial dopamine D2 receptor agonist effect may be a plausible alternative to current therapies, and would be effective in symptom reduction in psychotic individuals. It is also possible that therapies employing dopamine D1/D2 receptor agonists or COMT inhibitors will be beneficial for patients with negative symptoms in schizophrenia and bipolar disorder. The complex etiology of schizophrenia, and other psychiatric disorders, warrants the consideration of both genetic and epigenetic systems and the careful design of experiments to illumine the genetic mechanisms conferring liability for these disorders and the benefit of existing and new therapies.

Author(s): 
Abdolmaleky, Hamid M.
Thiagalingam, Sam
Wilcox, Marsha
Item Type: 
Journal Article
Publication Title: 
American Journal of Pharmacogenomics: Genomics-Related Research in Drug Development and Clinical Practice
Journal Abbreviation: 
Am J Pharmacogenomics
Publication Date: 
2005
Publication Year: 
2005
Pages: 
149-160
Volume: 
5
Issue: 
3
ISSN: 
1175-2203
Library Catalog: 
PubMed
Extra: 
PMID: 15952869

Turabian/Chicago Citation

Hamid M. Abdolmaleky, Sam Thiagalingam and Marsha Wilcox. 2005. "Genetics and epigenetics in major psychiatric disorders: dilemmas, achievements, applications, and future scope." American Journal of Pharmacogenomics: Genomics-Related Research in Drug Development and Clinical Practice 5: 3: 149-160.

Wikipedia Citation

<ref> {{Cite journal | doi = | issn = 1175-2203 | volume = 5 | pages = 149-160 | last = Abdolmaleky | first = Hamid M. | coauthors = Thiagalingam, Sam, Wilcox, Marsha | title = Genetics and epigenetics in major psychiatric disorders: dilemmas, achievements, applications, and future scope | journal = American Journal of Pharmacogenomics: Genomics-Related Research in Drug Development and Clinical Practice | date = 2005 | pmid = | pmc = }} </ref>