What you carry at this position in your DNA and what research says about it.
Bladder Cancer Risk: 5/10 evidence, 4 publications.
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Sample genotype (not yours): G/G
Typical Bladder Cancer Risk
Standard detoxification capacity keeps bladder cancer risk at the typical population baseline. Standard clearance rates also mean typical susceptibility to chemotherapy-related heart damage.
What this genotype means: Typical bladder cancer susceptibility; Standard clearance of anthracycline chemotherapy.
Sample genotype (not yours): G/T
Lower Bladder Cancer Risk
Increased enzyme expression helps clear environmental toxins, lowering the risk of bladder cancer. However, this variant may increase the risk of heart damage if treated with specific chemotherapy drugs.
What this genotype means: Reduced risk of bladder cancer; Increased risk of heart damage from anthracyclines.
Sample genotype (not yours): T/T
Lowest Bladder Cancer Risk
Maximised enzyme expression provides the strongest protection against bladder cancer by rapidly clearing toxins. However, this genotype carries the highest risk of heart damage if treated with certain chemotherapies.
What this genotype means: Strongly reduced risk of bladder cancer; Highest risk of heart damage from anthracyclines.
Gene function and biological role
Gene Function: The UGT1A1 gene belongs to the UDP-glucuronosyltransferase family, which plays a critical role in phase II drug metabolism and cellular detoxification. These enzymes facilitate the elimination of a wide range of foreign compounds, including environmental toxins and medications, by making them water-soluble. Within the UGT1A gene cluster, alternative splicing produces multiple functional isoforms that are highly expressed in the liver, kidneys, and bladder epithelium [1]. This localized expression is particularly important for neutralizing aromatic amines, which are potent carcinogens found in tobacco smoke and industrial pollutants [1]. Genetic variations in this cluster can significantly alter enzyme expression levels, directly impacting cancer susceptibility and drug clearance rates [1] [2].
Variant Impact: Located within the functional splicing form of the UGT1A6 enzyme, this synonymous coding variant is also known as Val209Val. Although it does not change the amino acid sequence of the protein, the genetic alteration significantly influences mRNA splicing and stability [1]. The minor T allele increases the expression of the functional enzyme, enhancing the bladder's ability to clear environmental carcinogens [1]. Conversely, this altered expression pattern is associated with reduced clearance of certain chemotherapy drugs and their metabolites [2]. Consequently, this single nucleotide change creates a trade-off between natural cancer protection and susceptibility to drug-induced side effects [1] [2].
Key Insight: This variant is a synonymous mutation, meaning it does not change the protein's amino acid sequence, yet it still dramatically alters gene expression and disease risk by affecting how mRNA is spliced.
Location: UGT1A6. Chromosome 2 · 2q37.1 · 233.7 Mb
Estimated prevalence by population
Global 89.6%; European 96.0%; African 78.2%; East Asian 94.3%; South Asian 91.6%; Americas 87.0%; Ashkenazi 94.9%; Finnish 91.7%; Middle Eastern 94.6%; Amish 94.6%.
Estimated GG genotype frequency.
Global 9.9%; European 4.0%; African 20.5%; East Asian 5.6%; South Asian 8.2%; Americas 12.6%; Ashkenazi 5.0%; Finnish 8.1%; Middle Eastern 5.3%; Amish 5.3%.
Estimated GT genotype frequency.
Global 0.5%; European < 0.1%; African 1.3%; East Asian 0.1%; South Asian 0.2%; Americas 0.5%; Ashkenazi 0.1%; Finnish 0.2%; Middle Eastern 0.1%; Amish 0.1%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cancer & Oncology
Urologic Cancers
Bladder Cancer. Evidence: 3/10. Source: PMID 22228101. Typical Risk.
Pharmacogenomics
Chemotherapy Response
Anthracycline Toxicity. Evidence: 5/10. Source: PMID 23441093. Typical Risk.
Showing effects for G/T genotype
Bladder Cancer. Evidence: 3/10. Source: PMID 22228101. Lower Risk.
Anthracycline Toxicity. Evidence: 5/10. Source: PMID 23441093. Increased Risk.
Showing effects for T/T genotype
Bladder Cancer. Evidence: 3/10. Source: PMID 22228101. Lowest Risk.
Anthracycline Toxicity. Evidence: 5/10. Source: PMID 23441093. Highest Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Inheriting two G alleles represents the baseline genetic profile for this region of chromosome 2. The UGT1A6 enzyme is expressed in the liver, kidneys, and bladder, where it plays a vital role in detoxifying environmental carcinogens [1]. Because this genotype does not increase enzyme expression, it does not provide the extra protection against bladder cancer seen with the minor T allele [1]. However, this standard expression level is highly favorable during certain cancer treatments. When exposed to anthracycline chemotherapy drugs like doxorubicin, individuals with this genotype maintain standard drug clearance [2]. This typical clearance rate significantly reduces the likelihood of toxic metabolite accumulation in heart tissue, resulting in a lower risk of chemotherapy-induced heart damage compared to T allele carriers [2].
Typical bladder cancer susceptibility; Standard clearance of anthracycline chemotherapy.
Sample genotype: GT (Heterozygous)
Possessing one copy of the uncommon T allele alters the splicing and expression of the UGT1A6 enzyme. This molecular change leads to significantly higher mRNA expression of the functional enzyme in the liver and bladder tissue [1]. Enhanced enzyme levels accelerate the detoxification and removal of harmful aromatic amines, which are common carcinogens found in tobacco smoke and industrial chemicals [1]. Consequently, this genotype is associated with a significantly lower risk of developing bladder cancer, particularly among individuals exposed to smoke [1]. On the other hand, this altered enzymatic activity presents a challenge during specific cancer therapies. If treated with anthracycline chemotherapy drugs such as doxorubicin or daunorubicin, carriers have an increased risk of developing cardiotoxicity [2]. The altered metabolism can lead to an accumulation of toxic drug byproducts in the heart muscle, necessitating closer cardiac monitoring during treatment [2].
Reduced risk of bladder cancer; Increased risk of heart damage from anthracyclines.
Sample genotype: TT (Homozygous)
Double copies of the protective T allele maximize the expression of the functional UGT1A6 enzyme. High levels of this enzyme in the bladder epithelium facilitate the rapid clearance of bioactivated aromatic amines and other environmental carcinogens [1]. This efficient detoxification process provides robust protection against bladder cancer, especially for those with a history of smoking or occupational chemical exposure [1]. Despite this significant health benefit, the genotype requires caution in oncology settings. Exposure to anthracycline chemotherapeutic agents like doxorubicin or daunorubicin carries a heightened risk of drug-induced heart damage [2]. The altered metabolic pathway slows the elimination of cardiotoxic chemotherapy metabolites, allowing them to build up in heart cells [2]. Oncologists often recommend enhanced cardiac monitoring or alternative protective strategies for patients with this genetic profile [2].
Strongly reduced risk of bladder cancer; Highest risk of heart damage from anthracyclines.
Variants with shared genetic architecture
rs2070959 · UGT1A6 Gene · Chr 2 · Gallstone Risk
rs6759892 · UGT1A6 Gene · Chr 2 · Drug and Toxin Metabolism
rs1105879 · UGT1A6 Gene · Chr 2 · Colorectal Cancer Risk
Content updated August 2026.
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