What you carry at this position in your DNA and what research says about it.
Dopamine Receptor Function: 5/10 evidence, 15 publications.
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Sample genotype (not yours): C/C
Mixed Risk Profile with Lower Addiction Vulnerability
This genotype is associated with a lower risk of nicotine and opioid dependence, but carries a higher risk of poor response to antipsychotic medications and increased side effects from ADHD stimulants.
What this genotype means: Lower risk of nicotine and opioid dependence; Higher risk of poor response to antipsychotic drugs; Increased likelihood of social withdrawal from ADHD stimulants.
Sample genotype (not yours): C/T
Typical Dopamine Receptor Function and Balanced Risks
This genotype represents a balanced profile, showing typical susceptibility to nicotine dependence and intermediate responses to psychiatric medications.
What this genotype means: Typical risk of nicotine dependence; Standard response to antipsychotic medications; Normal tolerance to ADHD stimulants.
Sample genotype (not yours): T/T
Higher Addiction Risk but Favorable Drug Response
This genotype is linked to an increased susceptibility to nicotine and opioid dependence, but correlates with a highly favorable response to antipsychotic treatments.
What this genotype means: Increased risk of nicotine and opioid dependence; Favorable response to antipsychotic therapies; Typical tolerance to ADHD stimulant medications.
Gene function and biological role
Gene Function: The DRD1 gene encodes the dopamine receptor D1, which is the most abundant dopamine receptor in the central nervous system. This receptor couples to G-proteins that stimulate adenylyl cyclase activity, playing a critical role in locomotor activity, reward pathways, and cognitive processes. Variations in this gene can alter receptor density and signaling efficiency in the prefrontal cortex and striatum. Consequently, it is widely studied in connection with neuropsychiatric conditions, substance addiction, and individual responses to therapeutic drugs.
Variant Impact: The rs4532 variant is located in the 5 prime untranslated region of the DRD1 gene, where it is thought to influence receptor translation and expression levels. The minor C allele has been associated with reduced expression of the D1 receptor compared to the major T allele. This alteration in receptor availability directly impacts dopamine signaling in brain regions responsible for reward reinforcement and executive control. As a result, this single nucleotide polymorphism modulates susceptibility to chemical dependencies and shapes how the brain responds to various psychiatric medications.
Key Insight: The same genetic variant that increases the risk of developing nicotine and opioid dependence also appears to make antipsychotic medications more effective.
Location: DRD1. Chromosome 5 · 5q35.2 · 175.4 Mb
Estimated prevalence by population
Global 9.6%; European 14.5%; African 1.2%; East Asian 2.0%; South Asian 16.7%; Americas 7.0%; Ashkenazi 10.0%; Finnish 14.1%; Middle Eastern 4.9%; Amish 23.3%.
Estimated CC genotype frequency.
Global 37.9%; European 47.1%; African 19.8%; East Asian 24.5%; South Asian 48.3%; Americas 38.9%; Ashkenazi 43.2%; Finnish 46.9%; Middle Eastern 34.4%; Amish 49.9%.
Estimated CT genotype frequency.
Global 52.6%; European 38.4%; African 79.0%; East Asian 73.4%; South Asian 34.9%; Americas 54.2%; Ashkenazi 46.8%; Finnish 39.0%; Middle Eastern 60.7%; Amish 26.8%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Neurology & Mental Health
Addiction & Reward
Nicotine Dependence. Evidence: 5/10. Source: PMID 18092181. Lower Risk.
Opioid Addiction Risk. Evidence: 5/10. Source: PMID 18092181. Lower Risk.
Neurodevelopmental Traits
Autism Susceptibility. Evidence: 3/10. Source: PMID 18205172. Lower Risk.
Pharmacogenomics
Antidepressant & Psychiatric Drug Response
Antipsychotic Response. Evidence: 3/10. Source: PMID 23036699. Poor Response.
ADHD Stimulant Side Effects. Evidence: 5/10. Source: PMID 23952191. Increased Side Effects.
Showing effects for C/T genotype
Nicotine Dependence. Evidence: 5/10. Source: PMID 18092181. Typical Risk.
Antipsychotic Response. Evidence: 3/10. Source: PMID 23036699. Intermediate Response.
ADHD Stimulant Side Effects. Evidence: 5/10. Source: PMID 23952191. Typical Response.
Showing effects for T/T genotype
Nicotine Dependence. Evidence: 5/10. Source: PMID 18092181. Increased Risk.
Opioid Addiction Risk. Evidence: 5/10. Source: PMID 18092181. Typical Risk.
Autism Susceptibility. Evidence: 3/10. Source: PMID 18205172. Increased Risk.
Antipsychotic Response. Evidence: 3/10. Source: PMID 23036699. Typical Response.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the minor C allele generally leads to lower expression of the dopamine D1 receptor. This reduction in receptor density appears to protect against the reinforcing effects of addictive substances, resulting in a lower risk of developing nicotine dependence [1]. Similarly, individuals with this genotype tend to experience a slower transition to opioid addiction and report less euphoria from opioids. However, the lower receptor availability can make certain medical treatments less effective. For instance, this genotype is linked to a significantly higher risk of treatment-resistant schizophrenia, meaning standard antipsychotic therapies may not work as well [2]. Furthermore, children with ADHD who have this genotype are more likely to experience social withdrawal as a side effect when treated with methylphenidate or dextroamphetamine [3].
Lower risk of nicotine and opioid dependence; Higher risk of poor response to antipsychotic drugs; Increased likelihood of social withdrawal from ADHD stimulants.
Sample genotype: CT (Heterozygous)
Carrying one copy of each allele results in intermediate dopamine D1 receptor expression and signaling. Research indicates that individuals with this genotype do not experience the highly elevated risks of nicotine dependence seen in those with the T/T genotype [1]. In terms of psychiatric care, the response to antipsychotic medications is generally typical, avoiding the high rates of treatment resistance associated with the C/C genotype [2]. However, some studies suggest a slightly modified response compared to the major homozygote, representing a middle ground in therapeutic efficacy. There is no significantly increased risk of social withdrawal when using common ADHD stimulant medications [3]. Overall, this heterozygous state maintains a balanced dopaminergic system, avoiding the extreme behavioral and pharmacological sensitivities of either homozygous genotype.
Typical risk of nicotine dependence; Standard response to antipsychotic medications; Normal tolerance to ADHD stimulants.
Sample genotype: TT (Homozygous)
Carrying two copies of the major T allele is associated with higher baseline expression of dopamine D1 receptors. While robust dopamine signaling supports cognitive performance, it also enhances the brain's reward response to addictive substances. Consequently, this genotype is significantly associated with an increased risk of nicotine dependence and tobacco smoking [1]. It is also linked to a faster transition to opioid addiction due to heightened drug-induced pleasure. On the positive side, higher receptor availability makes the dopaminergic system highly responsive to medical interventions. Individuals with this genotype show a favorable response to antipsychotic medications and a very low risk of treatment resistance [2]. Additionally, they do not exhibit an increased risk of social withdrawal when treated with standard ADHD stimulants [3].
Increased risk of nicotine and opioid dependence; Favorable response to antipsychotic therapies; Typical tolerance to ADHD stimulant medications.
Variants with shared genetic architecture
rs5326 · DRD1 Gene · Chr 5 · Mental Health Risk
rs686 · DRD1 Gene · Chr 5 · Addiction Risk
rs2514218 · DRD2 Gene · Chr 11 · Mental Health Risk
Significant association of DRD1 with nicotine dependence.
Content updated August 2026.
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