What you carry at this position in your DNA and what research says about it.
DNA Repair and Mitochondria: 7/10 evidence, 38 publications.
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Sample genotype (not yours): T/T
Typical DNA Repair and Mitochondrial Copy Number
Two copies of the reference aspartate allele are associated with baseline DNA repair activity. This genotype is linked to a slightly higher mitochondrial DNA copy number.
What this genotype means: Standard APEX1 enzyme structure; Slightly higher mitochondrial DNA copy number.
Sample genotype (not yours): G/G
Typical DNA Repair and Standard Mitochondrial Copy
Two copies of the variant glutamate allele encode a modified APEX1 enzyme. DNA repair efficiency and cellular health remain within the normal range.
What this genotype means: Modified APEX1 enzyme structure; Typical mitochondrial DNA copy number.
Sample genotype (not yours): T/G
Typical DNA Repair and Intermediate Mitochondrial Copy
One copy of each allele results in a mixture of aspartate and glutamate at position 148. Cellular DNA repair processes remain fully functional and typical.
What this genotype means: Mixed APEX1 enzyme structure; Intermediate mitochondrial DNA copy number.
Gene function and biological role
Gene Function: The APEX1 gene encodes apurinic/apyrimidinic endonuclease 1, a multifunctional enzyme central to the base excision repair pathway [1]. This pathway is the primary cellular mechanism for repairing DNA damage caused by oxidative stress, alkylation, and ionizing radiation [1]. Beyond its role in DNA repair, the encoded protein acts as a redox coactivator, regulating transcription factors involved in cell survival, inflammatory responses, and tumor growth [2]. It is also essential for maintaining mitochondrial genome integrity by repairing damaged mitochondrial DNA [3]. Consequently, variations in this gene can influence how cells respond to environmental toxins and oxidative stress [4].
Variant Impact: The rs1130409 variant is a missense mutation in the fifth exon of the APEX1 gene, resulting in an amino acid substitution from aspartate to glutamate at position 148 [1]. This specific change, often referred to as Asp148Glu, is located in the enzyme's N-terminal domain [1]. Although this substitution alters the local charge of the protein, biochemical studies indicate it does not significantly impair baseline DNA binding or endonuclease activity [5]. However, the variant has been widely studied for its potential subtle effects on DNA repair efficiency under conditions of high oxidative stress or heavy metal exposure [4]. ClinVar has officially classified this variant as benign, indicating it does not cause severe genetic disorders on its own [6].
Key Insight: This variant is highly common worldwide, with nearly half of the global population carrying at least one copy of the variant glutamate allele. While historically studied for links to various health conditions, large-scale clinical databases classify it as a benign genetic variation.
Location: APEX1. Chromosome 14 · 14q11.2 · 20.5 Mb
Estimated prevalence by population
Global 33.2%; European 27.1%; African 41.4%; East Asian 36.8%; South Asian 57.7%; Americas 34.5%; Ashkenazi 41.0%; Finnish 22.7%; Middle Eastern 28.9%; Amish 33.9%.
Estimated TT genotype frequency.
Global 48.1%; European 49.9%; African 45.9%; East Asian 47.7%; South Asian 36.5%; Americas 48.5%; Ashkenazi 46.0%; Finnish 49.9%; Middle Eastern 49.7%; Amish 48.6%.
Estimated TG genotype frequency.
Global 18.8%; European 23.0%; African 12.7%; East Asian 15.5%; South Asian 5.8%; Americas 17.0%; Ashkenazi 12.9%; Finnish 27.5%; Middle Eastern 21.4%; Amish 17.5%.
Estimated GG genotype frequency.
Showing effects for T/T genotype
Cancer & Oncology
General Cancer Risk
DNA Repair Capacity. Evidence: 5/10. Source: PMID 18823566. Typical.
Lifestyle, Fitness & Aging
Aging & Longevity
Mitochondrial DNA Copy Number. Evidence: 7/10. Source: PMID 37587338. Slightly Higher.
Nutrition & Metabolism
Blood Chemistry & Metabolites
Lead Sensitivity. Evidence: 3/10. Source: PMID 22466227. Typical.
Neurology & Mental Health
Cognitive Performance
Cognitive Performance. Evidence: 3/10. Source: PMID 29111564. Typical.
Showing effects for G/G genotype
Mitochondrial DNA Copy Number. Evidence: 7/10. Source: PMID 37587338. Typical.
Showing effects for T/G genotype
Mitochondrial DNA Copy Number. Evidence: 7/10. Source: PMID 37587338. Intermediate.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Carrying two copies of the reference T allele encodes the standard aspartate residue at position 148 of the APEX1 enzyme [1]. This genotype represents the most common genetic baseline globally, maintaining normal cellular responses to oxidative stress and routine DNA damage [2]. Research indicates that this genetic profile is associated with a slightly higher mitochondrial DNA copy number, which may reflect baseline mitochondrial replication dynamics [3]. While some early candidate-gene studies attempted to link this genotype to altered susceptibility to environmental toxins, large-scale genetic analyses and clinical databases like ClinVar support its classification as a benign, normal variant [4].
Standard APEX1 enzyme structure; Slightly higher mitochondrial DNA copy number.
Sample genotype: GG (Homozygous)
Carrying two copies of the variant G allele results in the exclusive production of the glutamate-containing APEX1 enzyme [1]. Although this amino acid change alters the local charge of the protein, extensive functional studies show that the enzyme's core DNA repair capabilities remain intact under normal physiological conditions [2]. This genotype is associated with a typical baseline mitochondrial DNA copy number compared to carriers of the reference allele [3]. Despite older, small-scale studies suggesting potential subtle increases in sensitivity to heavy metals or smoking-induced DNA damage, robust clinical evaluations have concluded that this genotype is benign [4]. It does not cause or predispose individuals to any known genetic disorders, representing a safe and common evolutionary variant.
Modified APEX1 enzyme structure; Typical mitochondrial DNA copy number.
Sample genotype: TG (Heterozygous)
Possessing one reference T allele and one variant G allele results in the production of both the aspartate and glutamate forms of the APEX1 protein [1]. This heterozygous profile is highly common, occurring in approximately 40% to 50% of most ancestral populations. Biochemical studies demonstrate that having a single copy of the glutamate variant does not compromise the overall efficiency of the base excision repair pathway [2]. Furthermore, mitochondrial DNA copy numbers in individuals with this genotype tend to fall in an intermediate range between the two homozygous groups [3]. Clinical databases confirm that this heterozygous state is entirely benign and carries no elevated risk for APEX1-related disorders [4]. It represents a normal genetic variation with no clinical significance.
Mixed APEX1 enzyme structure; Intermediate mitochondrial DNA copy number.
Variants with shared genetic architecture
rs1760944 · APEX1 Gene · Chr 14 · DNA Repair and Cancer Risk
rs180177132 · PALB2 Gene · Chr 16 · Hereditary Cancer Risk
rs35979828 · NFE2 Gene · Chr 12 · Blood Cell Production
Nuclear genetic control of mtDNA copy number and heteroplasmy in humans.
Identifying causal serum protein-cardiometabolic trait relationships using whole genome sequencing.
Content updated August 2026.
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