Imagine you're at a party; people are smiling, laughing, and talking, but you can't seem to join them. The idea of approaching someone makes you feel so uncomfortable you begin to lose your breath, and forget where you are — this is social anxiety. Now, researchers at the University of Bonn in Germany suspect a specific gene is behind the cause of social phobia.

The gene "SLC6A4" was identified as a possible trigger for the development of social anxiety disorder (SAD). SLC6A4 is a specific serotonin transporter that possesses a single nucleotide polymorphism (SNP), which can change the genetic code of an individual. This SNP is involved in transporting serotonin — a neurotransmitter that can affect mood and social behavior, among other things. Moreover, SLC6A4 is linked to a number of conditions, including alcoholism, clinical depression, obsessive-compulsive disorder (OCD), and even love.

Read More: 3 Signs You Have Social Anxiety, And How To Treat The Symptoms

“This is the largest association study so far into social phobia,” said Johannes Schumacher, study author and associate professor (Privatdozent)  from the Institute of Human Genetics at the University of Bonn, in a statement.

In the study, published in Psychiatric Genetics, researchers analyzed the DNA of 321 patients with social anxiety and compared it with 804 control patients. The team was looking for genetic variations in their DNA, since the cause of genetic illnesses often lie in SNPs. A total of 24 SNPs were suspected to be linked to the cause of social phobias and other mental disorders, but an SNP in SLC6A4 is believed to be the culprit in social anxiety.

“Until now, only a few candidate genes have been known that could be linked to this,” said Dr. Andreas Forstner, study author from the Institute of Human Genetics at the University of Bonn.

The researchers noted an interesting correlation between serotonin and social anxiety. Serotonin is known to suppress negative feelings of fear and depression, as doctors prescribed selective serotonin reuptake inhibitor (SSRIs) to help treat depression and anxiety. However, low levels of serotonin may not be linked to high social anxiety.

A 2015 study in JAMA Psychiatry found patients with social phobia have too much, not too little serotonin. Researchers found the more serotonin these patients produced, the more anxious they would become in social situations. They hypothesized this could be an attempt to compensate for the excess serotonin active in sending signals. This casts doubt on the belief that SSRIs help lower social anxiety by boosting serotonin levels.

A lot still needs to be investigated when it comes to serotonin and the gene SLC6A4. Despite the 2015 study, it's not clear whether low levels of serotonin lead to social anxiety, or whether social phobia leads to a decrease in serotonin.

Read More: 4 Drug-Free Ways To Treat Social Anxiety

"There is still a great deal to be done in terms of researching the genetic causes of this illness," said Forstner.

Forstner and his research team want to investigate further the links between DNA and social phobia.

“In order to achieve this goal, we need many more study participants who suffer from social anxiety,” said Stefanie Rambau, psychologist and study coordinator from the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy at University Hospital Bonn.

If you would like to get involved in the genetic research on social anxiety disorder, the research team is encouraging you to participate in their research online by visiting their website: Social Phobia Research.

Currently, 3.3 million American adults are affected by social anxiety in a given year.

Understanding the causes behind the disorder can help with better diagnosis and treatment procedures to improve the quality of life for patients.

Source: Forstner AJ, Rambau S, Friedrich et al.  Further evidence for genetic variation at the serotonin transporter gene SLC6A4 contributing toward anxiety. Psychiatr Genet. 2017.

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