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MTHFR 677C --> T genotype disrupts prefrontal function in schizophrenia through an interaction with COMT 158Val --> Met
Journal article   Open access   Peer reviewed

MTHFR 677C --> T genotype disrupts prefrontal function in schizophrenia through an interaction with COMT 158Val --> Met

Joshua L Roffman, Randy L Gollub, Vince D Calhoun, Thomas H Wassink, Anthony P Weiss, Beng C Ho, Tonya White, Vincent P Clark, Jill Fries, Nancy C Andreasen, …
Proceedings of the National Academy of Sciences - PNAS, Vol.105(45), pp.17573-17578
11/11/2008
DOI: 10.1073/pnas.0803727105
PMCID: PMC2582272
PMID: 18988738
url
https://doi.org/10.1073/pnas.0803727105View
Published (Version of record) Open Access

Abstract

Understanding how risk genes cumulatively impair brain function in schizophrenia could provide critical insights into its pathophysiology. Working memory impairment in schizophrenia has been associated with abnormal dopamine signaling in the prefrontal cortex, which is likely under complex genetic control. The catechol-O-methyltransferase (COMT) 158Val --> Met polymorphism (rs4680), which affects the availability of prefrontal dopamine signaling, consistently stratifies prefrontal activation during working memory performance. However, the low-dopamine COMT 158Val allele does not confer increased risk for schizophrenia, and its effects on prefrontal function are not specific to the disorder. In the setting of other genetic variants influencing prefrontal dopamine signaling, COMT 158Val --> Met genotype may exert disease-specific effects. A second polymorphism, methylenetetrahydrofolate reductase (MTHFR) 677C --> T (rs1801133), has been associated with overall schizophrenia risk and executive function impairment in patients, and may influence dopamine signaling through mechanisms upstream of COMT effects. We found that the hypofunctional 677T variant was associated with decreased working memory load-dependent activation in the prefrontal and insular cortices in 79 schizophrenia patients, but not in 75 demographically matched healthy controls. Further, significant MTHFR x COMT genotype interactions were observed, which differed by diagnostic group: Reduced prefrontal activation was associated with the 677T and 158Val alleles in patients, but with 677C/C and 158Met/Met genotype in controls. These findings are consistent with epistatic effects of the COMT and MTHFR polymorphisms on prefrontal dopamine signaling, and suggest that in schizophrenia patients, the MTHFR 677T allele exacerbates prefrontal dopamine deficiency. The findings also suggest the importance of weighing COMT effects on prefrontal function within the context of MTHFR genotype.
United States Humans Prefrontal Cortex - physiopathology Genotype Methylenetetrahydrofolate Reductase (NADPH2) - metabolism Signal Transduction - genetics Catechol O-Methyltransferase - genetics Polymorphism, Genetic Catechol O-Methyltransferase - metabolism Magnetic Resonance Imaging Schizophrenia - genetics Methylenetetrahydrofolate Reductase (NADPH2) - genetics Schizophrenia - physiopathology Dopamine - metabolism

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