Genetic Influences on Affective Disorders

Affective disorders, encompassing major depressive disorder and bipolar disorder, arise from a complex interplay of genetic, environmental and epigenetic factors. Family and twin studies have consistently shown moderate to high heritability, indicating that inherited variation accounts for a substantial proportion of individual risk. Genome-wide association studies have identified dozens of common variants of small effect distributed across neuroplasticity, synaptic function and stress-response pathways. In parallel, candidate-gene investigations have highlighted polymorphisms in serotonergic (for example, SLC6A4), neurotrophic (BDNF) and hypothalamic–pituitary–adrenal-axis genes (FKBP5, CRHR1) that modulate vulnerability to mood dysregulation. Gene–environment interaction models further emphasise how allelic variation can amplify or attenuate sensitivity to life stressors. Emerging epigenetic research has revealed that DNA methylation and non-coding RNAs can record early-life adversity and alter gene expression in neural circuits governing emotion. Increasingly, polygenic risk scores are being explored as prognostic tools in clinical practice. Together, these advances illuminate the molecular architecture of affective illness, foster stratified prevention strategies and open new avenues for personalised interventions.

Research from Nature Portfolio

Recent studies have elucidated how the serotonin transporter promoter polymorphism interacts with adverse life events to influence late-life depression. In a large cohort of older adults, carriers of the low-expression short allele exhibited significantly higher odds of depressive symptoms when exposed to lifetime or recent stressors, compared with long-allele homozygotes. This work demonstrates an age-dependent gene–environment interaction and suggests that genotype-guided assessment of stress susceptibility could improve prevention and treatment in elderly populations.

Genetic Influences on Affective Disorders publication trend

The graph below shows the total number of articles in genetic influences on affective disorders across all publications each year (not limited to Nature Index journals).

Technical terms

Single nucleotide polymorphism (SNP): A variation at a single base pair in the genome, often affecting gene function or regulation.

Polymorphism: A genetic variant that occurs commonly in a population and may influence trait susceptibility.

Gene–environment interaction: The phenomenon by which genetic predisposition modifies an individual’s response to environmental exposures.

DNA methylation: An epigenetic modification involving the addition of methyl groups to DNA, typically repressing gene expression.

Epigenetics: The study of heritable changes in gene activity that do not involve alterations in the DNA sequence.

5-HTTLPR: A polymorphic repeat region in the serotonin transporter gene promoter that affects transcriptional efficiency.

Polygenic risk score: An aggregate measure of genetic liability calculated from the sum of risk alleles weighted by effect sizes.

Heritability: The proportion of observed variation in a trait that can be attributed to genetic factors in a given population.

References

1. Associations of the serotonin transporter gene polymorphism, 5-HTTLPR, and adverse life events with late life depression in the elderly Lithuanian population. Scientific Reports (2023).
2. HTR1A, TPH2, and 5-HTTLPR Polymorphisms and Their Impact on the Severity of Depressive Symptoms and on the Concentration of Tryptophan Catabolites during Hepatitis C Treatment with Pegylated Interferon-α2a and Oral Ribavirin (PEG-IFN-α2a/RBV). Cells (2023).
3. Dopamine and Serotonin Transporter Genes Regulation in Highly Sensitive Individuals during Stressful Conditions: A Focus on Genetics and Epigenetics. Biomedicines (2024).
4. The effect of single nucleotide polymorphisms on depression in combination with coronary diseases: a systematic review and meta-analysis. Frontiers in Endocrinology (2024).