What you carry at this position in your DNA and what research says about it.
Antidepressant Side Effects: 6/10 evidence, 68 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): C/C
Higher Risk of Antidepressant Side Effects
Carrying two copies of the C allele is linked to a significantly higher likelihood of experiencing sexual dysfunction when taking SSRI antidepressants. There is also a stronger association with emotional traits like anger and impulsive behaviors.
What this genotype means: Increased risk of SSRI-induced sexual dysfunction; Higher tendency toward anger and aggression; Potentially better response to paroxetine.
Sample genotype (not yours): C/T
Typical Risk of Antidepressant Side Effects
Carrying one copy of each allele generally results in a typical risk profile for antidepressant-induced side effects. Emotional traits and treatment responses are usually close to the population average.
What this genotype means: Typical risk of SSRI-induced side effects; Average baseline serotonin receptor expression; Standard emotional and behavioral tendencies.
Sample genotype (not yours): T/T
Lower Risk of Antidepressant Side Effects
Carrying two copies of the T allele is associated with a lower risk of sexual side effects from SSRI antidepressants. This genotype is also linked to a lower likelihood of impulsive behaviors and anger.
What this genotype means: Lower risk of SSRI-induced sexual dysfunction; Decreased tendency toward anger and impulsive behaviors; Slightly lower risk of rheumatoid arthritis.
Gene function and biological role
Gene Function: The HTR2A gene encodes the serotonin 2A receptor, a key component of the brain's serotonin signaling system [1]. This receptor is widely distributed throughout the central nervous system and is heavily involved in modulating mood, cognition, and emotional behavior [1]. Because of its central role in neural communication, it is a primary target for many psychiatric medications, including antidepressants and antipsychotics [2]. Genetic variations within this gene can alter how receptors are expressed and how they respond to chemical signals [3]. Understanding these variations helps explain why different people experience varying therapeutic outcomes and side effects from the same medications [2].
Variant Impact: Located in the promoter region of the HTR2A gene, rs6311 is a single nucleotide polymorphism that influences gene transcription [3]. The genetic change alters a transcription factor binding site, which can modify the rate at which the serotonin receptor is produced [3]. Specifically, the C allele is associated with altered promoter activity and changes in receptor expression levels in the brain [4]. This molecular shift can affect baseline serotonin signaling and alter susceptibility to drug-induced receptor saturation [5]. As a result, this variant is widely studied for its impact on antidepressant tolerability and behavioral traits [5].
Key Insight: This variant lies in a promoter region where it directly alters transcription factor binding, meaning it physically changes how much serotonin receptor is built in the brain. It is one of the most heavily studied genetic predictors of sexual side effects from common antidepressants.
Location: HTR2A. Chromosome 13 · 13q14.2 · 46.9 Mb
Estimated prevalence by population
Global 35.6%; European 34.8%; African 37.1%; East Asian 17.0%; South Asian 36.4%; Americas 36.5%; Ashkenazi 25.3%; Finnish 43.9%; Middle Eastern 22.0%; Amish 61.8%.
Estimated CC genotype frequency.
Global 47.8%; European 48.4%; African 47.6%; East Asian 48.5%; South Asian 47.9%; Americas 47.8%; Ashkenazi 50.0%; Finnish 44.7%; Middle Eastern 49.8%; Amish 33.6%.
Estimated CT genotype frequency.
Global 16.6%; European 16.8%; African 15.3%; East Asian 34.5%; South Asian 15.8%; Americas 15.7%; Ashkenazi 24.7%; Finnish 11.4%; Middle Eastern 28.2%; Amish 4.6%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Pharmacogenomics
Antidepressant & Psychiatric Drug Response
Antidepressant Side Effects. Evidence: 6/10. Source: PMID 16710319. ~3.6x Higher Risk.
Antidepressant Response. Evidence: 5/10. Source: PMID 16874005. Stronger Response.
Neurology & Mental Health
Mood Disorders
Suicidal Thoughts. Evidence: 4/10. Source: PMID 18797395. Increased Risk.
Behavioral & Personality Traits
Anger and Aggression. Evidence: 4/10. Source: PMID 29120849. Higher Tendency.
Showing effects for C/T genotype
Antidepressant Side Effects. Evidence: 6/10. Source: PMID 16710319. Typical Risk.
Antidepressant Response. Evidence: 5/10. Source: PMID 16874005. Typical Response.
Suicidal Thoughts. Evidence: 4/10. Source: PMID 18797395. Typical Risk.
Anger and Aggression. Evidence: 4/10. Source: PMID 29120849. Typical.
Showing effects for T/T genotype
Antidepressant Side Effects. Evidence: 6/10. Source: PMID 16710319. Lower Risk.
Suicidal Thoughts. Evidence: 4/10. Source: PMID 18797395. Lower Risk.
Anger and Aggression. Evidence: 4/10. Source: PMID 29120849. Lower Tendency.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Serotonin receptors play a vital role in regulating sexual arousal and emotional control. Having the C/C genotype is associated with a 3.6-fold increase in the risk of developing sexual side effects, such as low arousal or erectile difficulties, when treated with selective serotonin reuptake inhibitors (SSRIs) [1]. This susceptibility may stem from lower baseline expression of the serotonin 2A receptor, making the system more vulnerable to drug-induced saturation [1]. Beyond medication side effects, this genotype has been linked to a higher frequency of anger- and aggression-related behaviors in healthy individuals [2]. Some clinical studies also suggest an association with impulsive and non-violent suicidal behaviors under severe stress [3]. Conversely, this profile is sometimes associated with a better therapeutic response to specific antidepressants like paroxetine [4]. It has also been identified as part of a genetic haplotype that slightly increases the risk of rheumatoid arthritis [5].
Increased risk of SSRI-induced sexual dysfunction; Higher tendency toward anger and aggression; Potentially better response to paroxetine.
Sample genotype: CT (Heterozygous)
An intermediate genetic profile often buffers against the more pronounced risks associated with homozygous genotypes. Individuals with the C/T genotype typically exhibit a standard risk of developing sexual dysfunction when taking SSRI antidepressants, showing no significant elevation compared to the general population [1]. Serotonin receptor expression levels in the brain are expected to be in the normal range, maintaining typical signaling dynamics [2]. While some studies have noted minor side-effect variations with specific medications like escitalopram, the overall clinical picture remains baseline [3]. Emotional traits, including anger expression and stress resilience, generally align with average population standards [4]. Suicidal behavior risk under stress is not significantly elevated or reduced by this variant alone [5]. This genotype represents a balanced genetic background that does not strongly tip the scales toward extreme sensitivity or high resistance.
Typical risk of SSRI-induced side effects; Average baseline serotonin receptor expression; Standard emotional and behavioral tendencies.
Sample genotype: TT (Homozygous)
Higher baseline expression of serotonin receptors may provide a protective buffer against certain drug-induced side effects. Having the T/T genotype is associated with a normal, lower risk of developing sexual dysfunction during SSRI antidepressant therapy [1]. This protective effect is thought to occur because higher receptor levels prevent the rapid saturation of the serotonergic pathway that causes arousal difficulties [1]. In behavioral studies, this genotype is consistently associated with lower levels of anger, aggression, and impulsive traits [2]. Researchers have also noted that the T allele appears to be protective against suicidal behavior during depressive episodes [3]. However, some pharmacogenomic studies suggest that individuals with this profile might have a slightly reduced response rate to paroxetine compared to C/C carriers [4]. Additionally, this genotype is associated with a lower risk of developing rheumatoid arthritis compared to those carrying the C allele [5].
Lower risk of SSRI-induced sexual dysfunction; Decreased tendency toward anger and impulsive behaviors; Slightly lower risk of rheumatoid arthritis.
Variants with shared genetic architecture
rs6313 · HTR2A Gene · Chr 13 · Serotonin Receptor Function
rs6314 · HTR2A Gene · Chr 13 · Episodic Memory
rs7997012 · HTR2A Gene · Chr 13 · Antidepressant Response
Genetics of serotonin receptors and depression: state of the art.
Pharmacogenetics of antidepressant response.
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com