Summary: Researchers identify a genetic variant in the serotonin transporter gene that is associated with social phobia.
Source: University of Bonn.
Study from the University of Bonn Supports a Role for Serotonin in Social Anxiety
People with social anxiety disorder, also known as social phobia, fear situations in which they may be judged by others. Sufferers commonly avoid public speaking, group interactions and everyday social tasks, which can lead to social withdrawal and increased reliance on mediated contact, such as social media or anonymous communication online. Around one in ten people will experience this disorder at some point in their lives. Researchers at the University of Bonn have found evidence that variation in a gene encoding a serotonin transporter in the brain may contribute to the condition. Serotonin is a neurotransmitter that can reduce feelings of anxiety and low mood. The team plans further research and is seeking more participants to expand the study. The results are published in the journal Psychiatric Genetics.
Symptoms and the Search for Genetic Contributors
Typical symptoms of social phobia include heart palpitations, trembling and shortness of breath in social situations. Many affected individuals avoid circumstances that could trigger negative judgment, preferring isolated or online communication. Social phobia arises through a combination of genetic predisposition and environmental factors. According to Dr. Andreas Forstner from the Institute of Human Genetics at the University of Bonn, understanding the genetic underpinnings remains an important research task. To date, only a limited number of candidate genes have been implicated.
Single Nucleotide Polymorphisms and the Study Design
In collaboration with the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at the University Hospital Bonn, Dr. Forstner and colleagues conducted a genetic association study. They analyzed DNA from 321 patients diagnosed with social anxiety disorder and compared those data to a control group of 804 individuals. The investigators focused on single nucleotide polymorphisms (SNPs) — single base-pair changes in DNA that vary between individuals. SNPs are common throughout the human genome and are often implicated in the genetic contribution to complex disorders.
The research team examined 24 SNPs that had been previously suspected, in a broad sense, of involvement in social phobia and related psychiatric conditions. According to Johannes Schumacher from the Institute of Human Genetics, this represents one of the largest association studies to date focused specifically on social phobia.
Clinical Information and Genetic Analysis
During the study, clinicians collected detailed information from participants about their symptoms and the severity of their social anxiety. Blood samples were taken to extract DNA for genotyping. Statistical analyses were used to examine whether particular genetic variants were associated with the diagnosis or with measures of symptom severity.
The analysis found evidence that one SNP in the serotonin transporter gene SLC6A4 is involved in social phobia. SLC6A4 encodes the protein responsible for transporting serotonin in the brain. Because serotonin can reduce anxiety and depressive symptoms, genetic variation that affects the transporter may influence vulnerability to social anxiety disorder. Selective serotonin reuptake inhibitors (SSRIs), which block the transporter and increase serotonin availability in the brain, are already used to treat anxiety and depressive disorders.
Next Steps and Invitation for Participants
The research team plans to investigate the relationship between DNA variation and social phobia in greater depth. To achieve this, they are recruiting additional participants who experience social anxiety. Stefanie Rambau, psychologist and study coordinator at the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at University Hospital Bonn, emphasizes that increased participation will help advance understanding of social phobia and improve future diagnosis and treatment.
Source: Andreas Forstner – University of Bonn
Image Source: Image used for illustration purposes.
Original Research: The study appears under the title “Further evidence for genetic variation at the serotonin transporter gene SLC6A4 contributing toward anxiety” in Psychiatric Genetics, published online March 2017. The paper reports genetic association results, discusses the potential role of SLC6A4 in anxiety-related traits, and highlights other loci of interest such as ANK3.
Abstract (Study Summary)
Social anxiety disorder (SAD) is a common, heritable psychiatric condition. Genetic studies focusing on SAD are limited, and only a few candidate genes have been implicated. This study examined whether SNPs previously associated with other psychiatric disorders also contribute to SAD and evaluated variants previously suggested to relate to the condition at a phenotypic level. Twenty-four SNPs were genotyped in a German sample comprising 321 SAD patients and 804 controls. Single-marker and quantitative association analyses were performed for SAD diagnosis, symptom severity, and harm avoidance personality traits.
After correction for multiple testing, none of the variants reached study-wide significance in the case-control comparison, although two SNPs showed nominal significance and one of these (rs140701) — located within SLC6A4 — had been reported in the same allelic direction in previous work. Quantitative analyses of symptom severity identified several nominally significant associations; among them rs10994359 near ANK3 showed the strongest signal and was also nominally associated with harm avoidance scores. Overall, the results provide additional support for involvement of SLC6A4 in anxiety-related traits and suggest that genetic variation near ANK3 may influence personality traits related to anxiety.