Psychiatric disorders often overlap, with shared symptoms making diagnosis challenging.
Conditions like depression and anxiety, schizophrenia and anorexia nervosa, or autism and ADHD frequently coexist, leaving scientists to wonder: why do these disorders appear together so often? While life experiences and environmental factors play a role, much of the answer lies in genetics.
Recent research has uncovered common genetic “hot spots” that may connect these disorders. In 2019, scientists from the Psychiatric Genomics Consortium, Harvard University, and the UNC School of Medicine identified 136 regions in the human genome associated with eight psychiatric conditions.
Among these, 109 regions were shared across multiple disorders, termed “pleiotropic” regions. However, it remained unclear how these shared genetic variations differed from those specific to a single disorder.
A new study led by Dr. Hyejung Won and Dr. Patrick Sullivan at the University of North Carolina has shed light on this question. Published in Cell, the research divides genetic variants into two groups: pleiotropic variants that influence multiple disorders and disorder-specific variants affecting just one.
Their findings suggest that pleiotropic variants may be promising targets for treatments capable of addressing multiple psychiatric conditions simultaneously.
The Role of Genetic Variants in Psychiatric Disorders
The human genome acts as a blueprint for the body, directing development and daily functions. Everyone’s genome is unique, but specific areas are prone to variations.
These genetic variants can disrupt biological processes, such as protein production or brain cell connections, influencing brain development and potentially contributing to psychiatric disorders.
In their 2019 study, researchers used genome-wide association studies (GWAS) to analyze the genetic basis of eight disorders: autism, ADHD, schizophrenia, bipolar disorder, major depressive disorder, Tourette syndrome, OCD, and anorexia.
They pinpointed 136 genomic hot spots linked to these conditions, with most of them shared across multiple disorders. The latest research by Won and her team dives deeper into these hot spots to better understand their function.
New Tools Reveal Key Variants
To investigate these regions, the researchers employed a cutting-edge technology called a massively parallel reporter assay.
They tested 17,841 genetic variants from the 136 hot spots in human neural cells to observe how they affected gene regulation—the process that determines how and when proteins are made. This analysis revealed 683 variants with a measurable impact on gene regulation.
These variants were then divided into two groups: pleiotropic variants, which were shared across disorders, and disorder-specific variants. By comparing the two, the researchers discovered several key differences.
What Makes Pleiotropic Variants Special?
Pleiotropic variants were found to be more active and remained active for longer periods during brain development compared to disorder-specific variants. This extended activity suggests that these variants influence multiple stages of neurodevelopment, potentially affecting various traits and disorders.
They were also more sensitive to disruptions, meaning changes in these genes could have a larger impact on brain function and health.
Additionally, pleiotropic variants were connected to genes that produce proteins involved in complex networks. Changes to these proteins could create ripple effects, disrupting multiple systems and contributing to shared symptoms across disorders.
Implications for Treatment
These findings provide valuable insights into why psychiatric disorders often overlap. The shared genetic factors identified in this study could become targets for new treatments that address multiple conditions at once.
For example, therapies aimed at stabilizing the effects of pleiotropic variants might help manage symptoms across several disorders, such as depression, anxiety, and schizophrenia.
Dr. Won emphasized the importance of this research: “If we can understand the genetic basis of pleiotropy, it might allow us to develop treatments targeting these shared genetic factors, helping treat multiple psychiatric disorders with a common therapy.”
The Path Forward
This study marks an important step toward unraveling the genetic complexity of psychiatric disorders. By identifying the shared genetic roots of these conditions, researchers hope to pave the way for more effective treatments that address overlapping symptoms. Future work will focus on targeting these variants, their associated genes, and the pathways they influence.
The findings highlight the interconnected nature of psychiatric disorders and the potential for breakthroughs in how they are treated. Understanding the shared genetic threads may eventually lead to therapies that improve the lives of millions affected by these challenging conditions.
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The research findings can be found in Cell.
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