Epistatic interaction between COMT and DTNBP1 modulates prefrontal function in mice and in humans

Area of Science:

• Neurogenetics
• Cognitive Neuroscience
• Behavioral Genetics

Background:

• Cognitive functions exhibit high heritability.
• Complex genetic interactions influencing cognition are understudied.
• Catechol-O-methyl transferase (COMT) and dystrobrevin-binding protein 1 (DTNBP1) are implicated in prefrontal cognitive function and dopamine signaling.

Purpose of the Study:

• To investigate the non-linear genetic interaction between COMT and DTNBP1.
• To examine the impact of this interaction on working memory and prefrontal cortical function.
• To understand the implications for complex trait genetics.

Main Methods:

• Utilized an animal model (mice) to study the effects of single and combined gene expression reduction.
• Employed functional magnetic resonance imaging (fMRI) in human volunteers (N=176) during a working memory task.
• Analyzed genetic variations in COMT (rs4680 Met allele) and DTNBP1 (dys haplotype).

Main Results:

• In mice, reduced expression of either COMT or DTNBP1 individually enhanced working memory.
• Conversely, simultaneous reduction of both COMT and DTNBP1 in mice led to working memory deficits.
• In humans, the COMT Met allele was associated with efficient prefrontal engagement, but less so with a specific DTNBP1 haplotype, indicating a similar non-linear interaction.

Conclusions:

• Demonstrated a consistent, non-linear, and multi-directional epistatic interaction between COMT and DTNBP1.
• Showed that a gene variant beneficial in one genetic context can be detrimental in another.
• Highlighted the importance of considering gene-gene interactions for understanding complex traits and for association analyses.