Genetic and epigenetic analyses of panic disorder in the post-GWAS era

Mapping Epigenetic Gene Variant Dynamics: Comparative Analysis of Frequency, Functional Impact and Trait Associations in African and European Populations

Epigenetic modifications influence gene expression levels, impact organismal traits, and play a role in the development of diseases. Therefore, variants in genes involved in epigenetic processes are likely to be important in disease susceptibility, and the frequency of variants may vary between populations with African and European ancestries. Here, we analyse an integrated dataset to define the frequencies, associated traits, and functional impact of epigenetic gene variants among individuals of African and European ancestry represented in the UK Biobank. We find that the frequencies of 88.4% of epigenetic gene variants significantly differ between these groups. Furthermore, we find that the variants are associated with many traits and diseases, and some of these associations may be population-specific owing to allele frequency differences. Additionally, we observe that variants associated with traits are significantly enriched for quantitative trait loci that affect DNA methylation, chromatin accessibility, and gene expression. We find that methylation quantitative trait loci account for 71.2% of the variants influencing gene expression. Moreover, variants linked to biomarker traits exhibit high correlation. We therefore conclude that epigenetic gene variants associated with traits tend to differ in their allele frequencies among African and European populations and are enriched for QTLs.

Inter- and transgenerational heritability of preconception chronic stress or alcohol exposure: Translational outcomes in brain and behavior

Chronic stress and alcohol (ethanol) use are highly interrelated and can change an individual's behavior through molecular adaptations that do not change the DNA sequence, but instead change gene expression. A recent wealth of research has found that these nongenomic changes can be transmitted across generations, which could partially account for the "missing heritability" observed in genome-wide association studies of alcohol use disorder and other stress-related neuropsychiatric disorders. In this review, we summarize the molecular and behavioral outcomes of nongenomic inheritance of chronic stress and ethanol exposure and the germline mechanisms that could give rise to this heritability. In doing so, we outline the need for further research to: (1) Investigate individual germline mechanisms of paternal, maternal, and biparental nongenomic chronic stress- and ethanol-related inheritance; (2) Synthesize and dissect cross-generational chronic stress and ethanol exposure; (3) Determine cross-generational molecular outcomes of preconception ethanol exposure that contribute to alcohol-related disease risk, using cancer as an example. A detailed understanding of the cross-generational nongenomic effects of stress and/or ethanol will yield novel insight into the impact of ancestral perturbations on disease risk across generations and uncover actionable targets to improve human health.

Examining individual differences in personality trait changes after negative life events

Personality traits can change throughout the entire life span, but people differ in their personality trait changes. To better understand individual differences in personality changes, we examined personal (personality functioning), environmental (environmental changes), and event-related moderators (e.g., perceived event characteristics) of personality trait changes. Therefore, we used a sample of 1069 participants who experienced a negative life event in the last 5 weeks and assessed their personality traits at five measurement occasions over 6 months. Employing preregistered multilevel lasso estimation, we did not find any significant effects. While exploratory analyses generally confirmed this conclusion, they also identified some effects that might being worth to be considered in future research (e.g., perceived impact and perceived social status changes were associated with changes in agreeableness after experiencing a relationship breakup). In total, our moderators explained less than 2% of variance in personality traits. Nonetheless, our study has several important implications for future research on individual differences in personality change. For example, future research should consider personal, environmental, and event-related moderators, use different analytical methods, and rely on highly powered samples to detect very small effects.

Associations of DNA methylation of HPA axis-related genes and neuroendocrine abnormalities in panic disorder

OBJECTIVE

The purpose of this study was to investigate the role of aberrant DNA methylation of hypothalamic-pituitary-adrenal (HPA) axis-related genes (CRHR1, CRHR2, CRH, FKBP5, HSP90AA1, NR3C1, and POMC) in panic disorder (PD) development. We investigated the correlation among gene methylation levels, adrenocorticotropic hormone (ACTH), cortisol, and PD severity in patients.

METHODS

We compared the methylation levels of HPA axis-related genes between 178 patients with PD and 184 healthy controls using MethylTarget. We then measured ACTH and cortisol levels using chemiluminescence. Disease severity was assessed using the Panic Disorder Severity Scale.

RESULTS

Compared with healthy controls, patients with PD displayed significantly higher levels of ACTH and cortisol, and significantly reduced methylation levels of CRHR1, FKBP5, HSP90AA1, and NR3C1 after correcting for multiple testing using the false discovery method. A significant positive correlation was observed between the methylation of CRHR1, CRHR2, and NR3C1 and ACTH levels in patients with PD, and methylation levels of CRHR1 and NR3C1 were significantly positively related to cortisol levels. In addition, a negative correlation was observed between PD severity and the methylation of CRH, CRHR1, CRHR2, and HSP90AA1.

CONCLUSION

Aberrant methylation of HPA axis-related genes may predict PD development and impact ACTH and cortisol levels.

Beyond canvas: behavioral onset of rfc1-expansion disease in an Italian family-causal or casual?

INTRODUCTION

Biallelic intronic AAGGG repeat expansion in the replication factor C subunit 1 (RFC1) gene was recently identified in two/third of patients with cerebellar ataxia, sensory neuropathy, and bilateral vestibular areflexia syndrome (CANVAS). The phenotypic spectrum has expanded since (i.e., parkinsonism, motor neuron involvement, cognitive decline); no behavioral symptoms have been reported yet.

CASE REPORT

We report an Italian family that met the diagnostic criteria for CANVAS, and RFC1-expansion was detected in five of seven. All the affected members presented behavioral-psychiatric symptoms (anxiety, panic attacks, alcohol abuse) before the multisystemic RFC1-expansion manifestation. The disease course was progressive, with ataxia and behavioral-cognitive aspects as the most disabling symptoms.

CONCLUSION

These behavioral-cognitive observations may broaden the RFC1-expansion phenotypic spectrum and highlight the importance of investigating the whole non-motor symptoms in ataxic patients.

Genetic contributions to anxiety disorders: where we are and where we are heading

Anxiety disorders are among the most common psychiatric disorders worldwide. They often onset early in life, with symptoms and consequences that can persist for decades. This makes anxiety disorders some of the most debilitating and costly disorders of our time. Although much is known about the synaptic and circuit mechanisms of fear and anxiety, research on the underlying genetics has lagged behind that of other psychiatric disorders. However, alongside the formation of the Psychiatric Genomic Consortium Anxiety workgroup, progress is rapidly advancing, offering opportunities for future research.Here we review current knowledge about the genetics of anxiety across the lifespan from genetically informative designs (i.e. twin studies and molecular genetics). We include studies of specific anxiety disorders (e.g. panic disorder, generalised anxiety disorder) as well as those using dimensional measures of trait anxiety. We particularly address findings from large-scale genome-wide association studies and show how such discoveries may provide opportunities for translation into improved or new therapeutics for affected individuals. Finally, we describe how discoveries in anxiety genetics open the door to numerous new research possibilities, such as the investigation of specific gene-environment interactions and the disentangling of causal associations with related traits and disorders.We discuss how the field of anxiety genetics is expected to move forward. In addition to the obvious need for larger sample sizes in genome-wide studies, we highlight the need for studies among young people, focusing on specific underlying dimensional traits or components of anxiety.