3 research outputs found
Genome-by-Trauma Exposure Interactions in Adults With Depression in the UK Biobank
IMPORTANCE: Self-reported trauma exposure has consistently been found to be a risk factor for major depressive disorder (MDD), and several studies have reported interactions with genetic liability. To date, most studies have examined gene-environment interactions with trauma exposure using genome-wide variants (single-nucleotide variations [SNVs]) or polygenic scores, both typically capturing less than 3% of phenotypic risk variance. OBJECTIVE: To reexamine genome-by-trauma interaction associations using genetic measures using all available genotyped data and thus, maximizing accounted variance. DESIGN, SETTING, AND PARTICIPANTS: The UK Biobank study was conducted from April 2007 to May 1, 2016 (follow-up mental health questionnaire). The current study used available cross-sectional genomic and trauma exposure data from UK Biobank. Participants who completed the mental health questionnaire and had available genetic, trauma experience, depressive symptoms, and/or neuroticism information were included. Data were analyzed from April 1 to August 30, 2021. EXPOSURES: Trauma and genome-by-trauma exposure interactions. MAIN OUTCOMES AND MEASURES: Measures of self-reported depression, neuroticism, and trauma exposure with whole-genome SNV data are available from the UK Biobank study. Here, a mixed-model statistical approach using genetic, trauma exposure, and genome-by-trauma exposure interaction similarity matrices was used to explore sources of variation in depression and neuroticism. RESULTS: Analyses were conducted on 148 129 participants (mean [SD] age, 56 [7] years) of which 76 995 were female (52.0%). The study approach estimated the heritability (SE) of MDD to be approximately 0.160 (0.016). Subtypes of self-reported trauma exposure (catastrophic, adult, childhood, and full trauma) accounted for a significant proportion of the variance of MDD, with heritability (SE) ranging from 0.056 (0.013) to 0.176 (0.025). The proportion of MDD risk variance accounted for by significant genome-by-trauma interaction revealed estimates (SD) ranging from 0.074 (0.006) to 0.201 (0.009). Results from sex-specific analyses found genome-by-trauma interaction variance estimates approximately 5-fold greater for MDD in male participants (0.441 [0.018]) than in female participants (0.086 [0.009]). CONCLUSIONS AND RELEVANCE: This cross-sectional study used an approach combining all genome-wide SNV data when exploring genome-by-trauma interactions in individuals with MDD; findings suggest that such interactions were associated with depression manifestation. Genome-by-trauma interaction accounts for greater trait variance in male individuals, which points to potential differences in depression etiology between the sexes. The methodology used in this study can be extrapolated to other environmental factors to identify modifiable risk environments and at-risk groups to target with interventions
Gene environment interplay in depression
Major depressive disorder (MDD) is a common psychiatric disorder and one of the
leading causes of disability worldwide. MDD is moderately heritable (~3040%),
suggesting both genetic and environmental effects are influential. Several strands
of evidence point to the possible presence of geneenvironment correlations and
geneenvironment interaction effects in MDD, although findings to date have been
relatively inconsistent.
Recently, research using available genetic and environmental data on biological
parents and offspring (trios), have shown that parental genetic nurturing effects are
detectable using polygenic scores (PGSs) in more heritable traits such as
educational attainment. Research findings also point to potential genebytrauma
exposure interaction effects involved in MDD. It is evident that data limitations may
result in power issues, confounding effects and biases, which impact reliable and
accurate quantification of these effects, highlighting the need for methods that
maximise statistical power and minimise bias and confounding when exploring
these effects.
This thesis aims to adapt existing statistical frameworks and use of data to explore
geneenvironment interplay effects, which are robust to the limitations of the
available data. Here, two large populationscale datasets, the UK Biobank
(N~150,000) and Generation Scotland: Scottish Family Health Study (N~2680 trios),
were utilised to explore genomebytrauma exposure interaction effects in
depression, as well as parental genetic nurturing effects in a range of traits
including MDD.
The research aims of this thesis included (1) implementing models exploring
parental genetic nurturing effects using available trio PGSs; (2) expanding these
models to explore mechanisms of genetic nurturing effects with available parental
phenotypic data, both addressed in chapter 2. Here, the quantification of parental
genetic nurturing effects using trio PGSs was found to be reliable and robust to data
limitations. However, expanding these models by including parental phenotypes
resulted in confounded effects. Simulation analyses demonstrated that the
confounding was induced by power issues associated with PGSs, highlighting the
need for improved measures of genetic variance. The final research aim (3) was to
explore genomebytrauma exposure interaction effects using relationship matrices
capturing genetic, trauma exposure and genomebytrauma exposure interaction
similarity between participants. Genomic relationship matrices utilised all available
genetic data, and thus, served as an improved representation of genetic variance.
Environmental relationship matrices utilised principal components, capturing
underlying dimensions of trauma exposure. A substantial proportion of MDD
variance was found to be attributed to genetic, trauma exposure and genome-by-trauma interaction effects. However, little insight was inferred regarding the
specificity and direction of trauma exposure involved in MDD manifestation, due to
the difficulty in interpreting the underlying dimensions of trauma exposure.
The two studies provide a strong rationale for the use of improved measures of
genetic and environmental components of MDD. Specifically, findings from chapter
2 highlight the need for measures that capture a substantial proportion of genetic
variance to explore these complex geneenvironment interplay effects. Chapter 3
results demonstrated how leveraging all available genetic data can uncover
substantial effects that were previously missed. Evaluations of study designs
highlight how future work can incorporate omics (e.g. methylation) data to improve
measures of environmental factors, which would aid translational interpretation of
results obtained from these models. Methylation data could help identify additional
trait associated genetic loci as well as their mode of action, and hence, specific drug
targets; which may not have been previously identified by traditional analyses such
as genomewide association studies (GWAS) not containing the relevant genetic
variants