What you carry at this position in your DNA and what research says about it.
Detoxification Capacity: 6/10 evidence, 14 publications.
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Sample genotype (not yours): A/A
Reduced Detoxification and Higher Health Risks
Reduced Phase 2 detoxification capacity can lead to slower clearance of environmental toxins. This genotype is linked to a higher risk of asthma, respiratory allergies, and schizophrenia.
What this genotype means: Slower clearance of environmental toxins; Higher risk of asthma and allergies; Increased risk of chemotherapy-induced anemia.
Sample genotype (not yours): A/G
Moderate Detoxification and Intermediate Health Risks
Moderate protection against environmental toxins is provided by intermediate enzyme activity. This genotype is linked to a slightly elevated risk of asthma and respiratory allergies.
What this genotype means: Moderate Phase 2 detoxification; Slightly higher risk of asthma; Mixed chemotherapy metabolism.
Sample genotype (not yours): G/G
Robust Detoxification and Typical Health Risks
Robust Phase 2 detoxification helps your liver efficiently clear environmental toxins and heavy metals. This genotype is associated with a typical risk of asthma, respiratory allergies, and schizophrenia.
What this genotype means: Robust Phase 2 detoxification; Typical risk of asthma and allergies; Higher omega-3 fatty acid levels.
Gene function and biological role
Gene Function: Glutathione S-transferase alpha 1, encoded by the GSTA1 gene, is a key Phase 2 detoxification enzyme highly expressed in the liver [1]. This enzyme catalyzes the conjugation of reduced glutathione to a wide variety of electrophilic compounds, including environmental toxins, carcinogens, and therapeutic drugs [1] [2]. By neutralizing these reactive molecules, the enzyme protects cells from oxidative stress and genetic damage [2]. It also plays a vital role in metabolizing endogenous compounds like bilirubin and lipid peroxidation products [1]. Variations in this gene can significantly alter enzyme expression levels, directly impacting an individual's capacity to clear toxins and process medications [2].
Variant Impact: Located in the promoter region of the GSTA1 gene, the rs3957357 variant is a single nucleotide polymorphism [3]. This genetic change alters the transcriptional activity of the promoter, directly affecting how much GSTA1 enzyme the liver produces [3] [4]. The G allele corresponds to the high-activity GSTA1*A promoter variant, which maintains normal, robust enzyme expression [3]. Conversely, the A allele represents the low-activity GSTA1*B promoter variant, which significantly reduces enzyme production [3] [4]. Consequently, individuals carrying the A allele have a diminished capacity for glutathione-based Phase 2 detoxification, leaving cells more vulnerable to oxidative stress and environmental toxins [4].
Key Insight: This variant acts like a dimmer switch for your liver's primary detoxification enzyme, with the low-activity version reducing enzyme levels by up to several-fold.
Location: GSTA1. Chromosome 6 · 6p12.2 · 52.8 Mb
Estimated prevalence by population
Global 14.2%; European 18.1%; African 10.0%; East Asian 1.6%; South Asian 11.6%; Americas 9.1%; Ashkenazi 18.7%; Finnish 19.1%; Middle Eastern 15.3%; Amish 11.6%.
Estimated AA genotype frequency.
Global 45.6%; European 48.9%; African 43.2%; East Asian 22.1%; South Asian 44.9%; Americas 42.1%; Ashkenazi 49.1%; Finnish 49.2%; Middle Eastern 47.6%; Amish 44.9%.
Estimated AG genotype frequency.
Global 40.2%; European 33.0%; African 46.8%; East Asian 76.2%; South Asian 43.5%; Americas 48.7%; Ashkenazi 32.2%; Finnish 31.7%; Middle Eastern 37.1%; Amish 43.4%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Pharmacogenomics
Drug Metabolism Enzyme Activity
Phase 2 Detoxification. Evidence: 3/10. Source: PMID 24919441. Reduced Capacity.
Chemotherapy Response
Chemotherapy Response. Evidence: 6/10. Source: PMID 19448608. Slower Clearance.
Immunity & Inflammation
Allergy & Hypersensitivity
Asthma and Allergies. Evidence: 3/10. Source: PMID 24471578. Higher Risk.
Neurology & Mental Health
Psychotic Disorders
Schizophrenia. Evidence: 3/10. Source: PMID 32021204. Higher Risk.
Nutrition & Metabolism
Macronutrient Metabolism
Omega-3 Fatty Acids. Evidence: 6/10. Source: PMID 41044249. Lower Levels.
Showing effects for A/G genotype
Phase 2 Detoxification. Evidence: 3/10. Source: PMID 24919441. Moderate Capacity.
Asthma and Allergies. Evidence: 3/10. Source: PMID 24471578. Slightly Higher Risk.
Schizophrenia. Evidence: 3/10. Source: PMID 32021204. Slightly Higher Risk.
Omega-3 Fatty Acids. Evidence: 6/10. Source: PMID 41044249. Typical Levels.
Showing effects for G/G genotype
Phase 2 Detoxification. Evidence: 3/10. Source: PMID 24919441. Robust Capacity.
Chemotherapy Response. Evidence: 6/10. Source: PMID 19448608. Faster Clearance.
Asthma and Allergies. Evidence: 3/10. Source: PMID 24471578. Typical Risk.
Schizophrenia. Evidence: 3/10. Source: PMID 32021204. Typical Risk.
Omega-3 Fatty Acids. Evidence: 6/10. Source: PMID 41044249. Higher Levels.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Significant reduction in the expression of the GSTA1 enzyme in the liver is characteristic of the A/A genotype [1]. This low-activity state compromises Phase 2 detoxification, making it more difficult for the body to neutralize and eliminate environmental chemicals, heavy metals, and mold toxins [1]. Over time, the slower clearance of these compounds can lead to increased oxidative stress and cellular damage [2]. Clinical studies have consistently linked this reduced enzyme activity to a significantly higher risk of developing asthma and respiratory allergies [2]. Additionally, this genotype is associated with an increased susceptibility to schizophrenia and greater severity of sensory symptoms [3]. On a nutritional level, individuals with this genotype tend to have lower circulating levels of beneficial omega-3 fatty acids [4]. In oncology, however, the slower drug metabolism associated with this genotype can sometimes lead to increased chemotherapy survival rates, though at the cost of higher toxicity, such as anemia [5].
Slower clearance of environmental toxins; Higher risk of asthma and allergies; Increased risk of chemotherapy-induced anemia.
Sample genotype: AG (Heterozygous)
Intermediate expression of the GSTA1 detoxification enzyme occurs with the A/G genotype [1]. This moderate enzyme level provides a balanced but slightly reduced capacity to clear environmental chemicals, mold toxins, and heavy metals compared to the high-activity genotype [1]. As a result, the body may experience slightly higher levels of oxidative stress under heavy toxin exposure [2]. Clinical research indicates that this intermediate state is associated with a mildly increased susceptibility to asthma and respiratory allergies [2]. There is also a slightly higher risk of schizophrenia, though environmental factors play a major role [3]. In nutritional profiles, this genotype is associated with typical levels of omega-3 fatty acids [4]. In a medical context, carrying one A allele can lead to slower metabolism of certain chemotherapy drugs, which may enhance treatment efficacy but also increase the risk of side effects such as anemia [5].
Moderate Phase 2 detoxification; Slightly higher risk of asthma; Mixed chemotherapy metabolism.
Sample genotype: GG (Homozygous)
Robust expression of the GSTA1 enzyme in the liver is maintained by the G/G genotype [1]. This robust enzyme level allows for efficient Phase 2 detoxification, where glutathione is attached to environmental toxins, heavy metals, and mold toxins to safely eliminate them from the body [1]. Consequently, this genotype is protective against the oxidative stress and cellular damage that can trigger inflammatory conditions [2]. Studies show that individuals with this genotype have a typical, non-elevated risk of developing asthma and respiratory allergies [2]. Furthermore, this high-activity state is associated with a typical risk of schizophrenia and lower severity of related symptoms [3]. In terms of nutrition, the G allele is linked to higher circulating levels of beneficial omega-3 fatty acids and docosahexaenoic acid (DHA) [4]. Finally, during certain chemotherapy regimens, this genotype is associated with faster drug clearance, which may reduce the risk of treatment-related side effects like anemia [5].
Robust Phase 2 detoxification; Typical risk of asthma and allergies; Higher omega-3 fatty acid levels.
Variants with shared genetic architecture
rs3957356 · GSTA1 Gene · Chr 6 · Chemotherapy Metabolism
rs1800566 · NQO1 Gene · Chr 16 · Toxin Detoxification
rs1695 · GSTP1 Gene · Chr 11 · Detoxification and Lung Health
Polymorphisms of NRF2 and NRF2 target genes in urinary bladder cancer patients.
GSTA1*-69C/T and GSTO2*N142D as asthma- and allergy-related risk factors in Italian adult patients.
Effects of GSTA1 and GPX3 Polymorphisms on the Risk of Schizophrenia in Chinese Han Population.
A genetic map of human metabolism across the allele frequency spectrum.
Content updated August 2026.
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