What you carry at this position in your DNA and what research says about it.
Hormone and Vitamin D Levels: 6/10 evidence, 15 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): T/T
Higher Vitamin D and Testosterone Levels
Higher circulating levels of vitamin D and testosterone are characteristic of this genetic profile. Slower metabolism of certain medications, such as the antiseizure drug lamotrigine, may also lead to a more pronounced therapeutic response.
What this genotype means: Higher baseline vitamin D levels; Slower clearance of lamotrigine.
Sample genotype (not yours): G/G
Lower Vitamin D and Testosterone Levels
Lower circulating levels of vitamin D and testosterone are associated with this genetic profile. It also correlates with faster metabolism of certain medications, which may reduce their side effects.
What this genotype means: Lower baseline vitamin D levels; Reduced risk of certain olanzapine side effects.
Sample genotype (not yours): T/G
Typical Vitamin D and Hormone Levels
Intermediate levels of vitamin D and testosterone are typical for this genetic profile. Drug metabolism rates for medications like lamotrigine and olanzapine are generally balanced.
What this genotype means: Typical baseline vitamin D levels; Standard drug clearance rates.
Gene function and biological role
Gene Function: The UGT1A10 gene belongs to the UDP-glucuronosyltransferase family, a group of enzymes essential for the clearance of various compounds from the body. These enzymes perform glucuronidation, a process that attaches a sugar molecule to toxins, hormones, and medications to make them water-soluble for excretion. Specifically, UGT1A10 is highly expressed in the gastrointestinal tract, where it acts as a first-line barrier against ingested carcinogens and foreign chemicals. It also plays a role in regulating steroid hormones and bile acids within local tissues. Variations in this gene family can significantly alter how efficiently the body processes environmental toxins and therapeutic drugs.
Variant Impact: The rs2011425 variant is a single nucleotide polymorphism located within the UGT1A gene cluster on chromosome 2. This genetic change alters the coding sequence, which can influence the metabolic activity of multiple enzymes in this family, including UGT1A4 and UGT1A10. Because these enzymes process a wide range of substances, the variant has been linked to differences in circulating hormone levels and drug clearance rates. In particular, it affects how the body metabolizes sex hormones like testosterone and essential nutrients like vitamin D. It also serves as a key marker for predicting individual responses to several neuropsychiatric and immunosuppressive medications.
Key Insight: This single genetic variant acts as a metabolic dial, simultaneously influencing your natural vitamin D levels and how quickly your liver processes common medications.
Location: UGT1A10. Chromosome 2 · 2q37.1 · 233.7 Mb
Estimated prevalence by population
Global 81.5%; European 83.4%; African 80.9%; East Asian 65.0%; South Asian 65.0%; Americas 79.2%; Ashkenazi 80.6%; Finnish 90.6%; Middle Eastern 75.8%; Amish 98.2%.
Estimated TT genotype frequency.
Global 17.4%; European 15.9%; African 18.1%; East Asian 31.2%; South Asian 31.3%; Americas 19.6%; Ashkenazi 18.4%; Finnish 9.2%; Middle Eastern 22.5%; Amish 1.7%.
Estimated TG genotype frequency.
Global 1.0%; European 0.8%; African 1.0%; East Asian 3.8%; South Asian 3.8%; Americas 1.2%; Ashkenazi 1.0%; Finnish 0.2%; Middle Eastern 1.7%; Amish < 0.1%.
Estimated GG genotype frequency.
Showing effects for T/T genotype
Nutrition & Metabolism
Vitamin & Mineral Metabolism
Vitamin D Levels. Evidence: 6/10. Source: PMID 32059762. Higher.
Endocrine & Reproductive
Hormone Levels & Endocrine Regulation
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Higher.
Pharmacogenomics
Antiepileptic & Mood-Stabilizer Response
Lamotrigine Metabolism. Evidence: 5/10. Source: PMID 24820767. Slower Metabolism.
Antidepressant & Psychiatric Drug Response
Olanzapine Side Effects. Evidence: 5/10. Source: PMID 32070304. Typical Severity.
Immunosuppressant & Biologic Response
Tacrolimus Metabolism. Evidence: 5/10. Source: PMID 40604035. Faster Metabolism.
Showing effects for G/G genotype
Vitamin D Levels. Evidence: 6/10. Source: PMID 32059762. Lower.
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Lower.
Lamotrigine Metabolism. Evidence: 5/10. Source: PMID 24820767. Faster Metabolism.
Olanzapine Side Effects. Evidence: 5/10. Source: PMID 32070304. Decreased Severity.
Tacrolimus Metabolism. Evidence: 5/10. Source: PMID 40604035. Typical.
Showing effects for T/G genotype
Vitamin D Levels. Evidence: 6/10. Source: PMID 32059762. Typical.
Testosterone Levels. Evidence: 8/10. Source: PMID 32042192. Typical.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Enzymatic activity associated with this profile leads to a slower clearance of several key hormones and therapeutic drugs. Large-scale genetic studies show that carrying two copies of the T allele is linked to higher baseline levels of testosterone [1] and increased concentrations of vitamin D [2]. In the context of medication, this slower metabolic rate means that drugs like lamotrigine remain in the bloodstream longer, which has been associated with improved therapeutic efficacy in clinical studies [3]. Conversely, some medications like the immunosuppressant tacrolimus may be processed more rapidly [4]. Understanding these metabolic tendencies helps explain natural variations in hormone balance and drug sensitivity. While these genetic influences are notable, overall health outcomes are heavily shaped by diet, lifestyle, and other environmental factors.
Higher baseline vitamin D levels; Slower clearance of lamotrigine.
Sample genotype: GG (Homozygous)
Accelerated enzymatic activity in this profile leads to the rapid clearance of several hormones and medications. Genetic analyses indicate that carrying two copies of the G allele is associated with lower baseline levels of both testosterone [1] and vitamin D [2]. This rapid metabolism also extends to therapeutic drugs, meaning that medications like lamotrigine are cleared from the system more quickly, which can sometimes reduce their steady-state concentrations [3]. However, this faster clearance can also be highly beneficial for tolerability; for instance, individuals with this profile often experience a decreased severity of autonomic nervous system side effects when treated with olanzapine [4]. These findings highlight how a single genetic variant can create complex trade-offs between hormone regulation and drug tolerability.
Lower baseline vitamin D levels; Reduced risk of certain olanzapine side effects.
Sample genotype: TG (Heterozygous)
Balanced enzymatic activity in the UGT1A pathway typically results in moderate hormone levels and standard drug clearance rates. Having one copy of each allele generally positions an individual between the higher and lower extremes of vitamin D and testosterone concentrations observed in the population [1] [2]. For individuals taking the antiseizure medication lamotrigine, this intermediate profile is associated with a faster clearance rate compared to those with the T/T genotype, so the drug reaches lower levels [3]. Similarly, the metabolism of the antipsychotic drug olanzapine is slightly accelerated, which may influence both drug exposure and the likelihood of experiencing specific autonomic side effects [4]. This genetic middle ground provides a stable baseline for processing both internal hormones and external compounds. Most clinical guidelines treat this intermediate status as a standard reference point for therapeutic monitoring.
Typical baseline vitamin D levels; Standard drug clearance rates.
Variants with shared genetic architecture
rs11892031 · UGT1A10 Gene · Chr 2 · Bladder Cancer Risk
rs34983651 · UGT1A10 Gene · Chr 2 · Gilbert's Syndrome Risk
rs3732218 · UGT1A10 Gene · Chr 2 · Drug and Hormone Levels
Genetic analyses implicate complex links between adult testosterone levels and health and disease.
Genome-wide Association Study for Vitamin D Levels Reveals 69 Independent Loci.
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