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Open AccessJournal ArticleDOI

Differential expression of human COMT alleles in brain and lymphoblasts detected by RT-coupled 5′ nuclease assay

TLDR
The RT-coupled 5′ nuclease assay is a reliable method for the quantitative evaluation of cis-acting regulatory effects of catechol-O-methyltransferase (COMT) enzyme activity and predicts higher mRNA expression in both brain and lymphoblasts.
Abstract
A common polymorphism, Val158Met, alters catechol-O-methyltransferase (COMT) enzyme activity and has been linked to psychiatric phenotypes. Bray et al. (2003) reported that COMT is subject to differential allele expression in brain, finding modest (13–22%) underexpression of a haplotype containing Val158. However, disparate findings by another group who used the same method, but in lymphoblasts, raise the issues of tissue specificity, magnitude of differential expression, and identity of loci altering expression. We measured COMT allele expression ratios in heterozygous human lymphoblast cell lines and brains. Using transcribed single nucleotide polymorphisms as endogenous reporters, we developed an RT-coupled 5′ nuclease assay for allele expression ratios and applied it to 63 COMT rs4818(C>G) heterozygotes and 68 Val158Met [rs4680(G>A)] heterozygotes. For rs4818(C>G), the C allele was overexpressed relative to the G allele in 18 of 27 lymphoblast lines and 23 of 36 brains. For Val158Met, Met158 was overexpressed relative to Val158 in all (29 of 29) lymphoblast lines and all (39 of 39) brains. Each of the 22 rs4818 heterozygotes without differential allele expression was a Val158/Val158 homozygote. The Met158 allele was overexpressed by 65–77% when compared with Val158 in lymphoblasts and brain. Haplotype augmented ability to predict expression in brain only. However, the expression of the Val158 allele on the high-expressing haplotype was only 19% higher than Val158 alleles on the other haplotype background. COMT alleles are differentially expressed. The Met158 allele predicts higher mRNA expression in both brain and lymphoblasts. As exemplified here, the RT-coupled 5′ nuclease assay is a reliable method for the quantitative evaluation of cis-acting regulatory effects.

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Journal ArticleDOI

The genetics of addictions: Uncovering the genes

TL;DR: The addictions are common chronic psychiatric diseases that today are prevented and treated using relatively untargeted and only partially effective methods, but future understanding of addictions will be enhanced by the identification of genes that have a role in altered substance-specific vulnerabilities such as variation in drug metabolism or drug receptors.
Journal ArticleDOI

The catechol-O-methyl transferase (COMT) gene as a candidate for psychiatric phenotypes: evidence and lessons

TL;DR: The current state of evidence of catechol-O-methyl transferase, one of the most studied genes for psychosis, is considered and the implications both for further studies of COMT and more generally for studies of other genes are considered.
Journal ArticleDOI

Genetic approaches to addiction: genes and alcohol.

TL;DR: Although the genetic bases of alcoholism remain largely unknown, there are reasons to think that more genes will be discovered in the future and genome-wide analyses of transcripts and chromatin remodeling promise an increase in understanding of the genome function and of the mechanisms through which gene and environment cause diseases.
Journal ArticleDOI

Genetic architecture of human pain perception

TL;DR: It is proposed how both rare deleterious genetic variants and common genetic polymorphisms are mediators of human pain perception and clinical pain phenotypes.
References
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TL;DR: Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems are indicated.
Journal ArticleDOI

A Comparison of Bayesian Methods for Haplotype Reconstruction from Population Genotype Data

TL;DR: A new algorithm is introduced that combines the modeling strategy of one method with the computational strategies of another and outperforms all three existing methods for inferring haplotypes from genotype data in a population sample.
Journal ArticleDOI

Effect of COMT Val108/158 Met genotype on frontal lobe function and risk for schizophrenia.

TL;DR: The data suggest that the COMT Val allele, because it increases prefrontal dopamine catabolism, impairs prefrontal cognition and physiology, and by this mechanism slightly increases risk for schizophrenia.
Journal ArticleDOI

Human catechol-O-methyltransferase pharmacogenetics: description of a functional polymorphism and its potential application to neuropsychiatric disorders.

TL;DR: The identification of a gentic marker associated with significant alterations in enzyme activity will facilitate the analysis of a possible role for the COMT gene in neuropsychiatric conditions in which abnormalities in catecholamine neurotransmission are believed to occur.
Journal ArticleDOI

Enzymatic O-methylation of epinephrine and other catechols.

TL;DR: The properties of an enzyme that transfers the methyl group of S-adenosylmethionine to the hydroxyl group in position 3 of epinephrine and other catechols are described.
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