ATM rs3218707: What Your Genotype Means
ATM rs3218707 is a single-nucleotide variant in the ATM gene that has been studied as a possible contributor to breast cancer risk. It is one of several variants considered in cumulative risk research, but this result alone does not diagnose cancer or predict what will happen to an individual.
What each genotype means
Typical ATM genotype
This genotype represents the most common form of the ATM gene at this specific location. Research does not associate this specific configuration with the increased breast cancer risk profiles sometimes linked to rare, pathogenic ATM variants.
This is the most common genotype observed across global populations.
Potential risk-associated carrier
Carrying one copy of the G allele at this position is noted in some studies as part of a broader set of variants that may contribute to a cumulative, moderate increase in breast cancer risk. Because ATM-related risk is complex and often depends on the specific functional impact of a variant, this result should be viewed as a statistical association rather than a diagnostic indicator.
The G allele is present at a global minor allele frequency of approximately 1.2%, making this heterozygous genotype relatively uncommon.
Increased risk-associated genotype
Individuals with this genotype carry two copies of the G allele, which has been identified in research as a variant contributing to a cumulative increased risk for breast cancer. While this association is recognized, the overall risk is influenced by many genetic and environmental factors, and this finding does not constitute a medical diagnosis.
This homozygous genotype is rare, occurring in a small fraction of the population consistent with the reported minor allele frequency of 0.012.
What rs3218707 Is and Where It Fits
The ATM gene, short for Ataxia-Telangiectasia Mutated, is located on chromosome 11. rs3218707 is a single-nucleotide polymorphism, or SNP, within this gene. A SNP is a difference at one position in the DNA sequence. People inherit two copies of most genes, so a genetic report may show two letters for this position, representing the alleles inherited from each parent. Many SNPs are ordinary sources of human genetic variation and do not cause disease. Researchers study particular SNPs when population data suggest that they may be associated with a health trait or disease. For rs3218707, the catalog describes the variant as one of several SNPs identified as contributing to a cumulative increased risk for breast cancer. That description refers to a statistical association observed in research populations; it does not establish that the SNP alone causes cancer or that every carrier will have the same outcome.
What the ATM Gene Does
ATM is important for maintaining the integrity of the genome. Its protein acts as a sensor for DNA damage, particularly damage involving double-strand breaks. When damage occurs, the ATM protein helps initiate cellular responses that can repair the DNA or, when repair is not possible, lead to programmed cell death. These processes help prevent damaged cells from continuing to divide and potentially forming tumors. The role of the gene helps explain why ATM has been studied in cancer research. However, the existence of a biologically important gene does not mean that every variant within it has the same effect. Pathogenic mutations in ATM are associated with certain inherited cancer risks and with the rare condition ataxia-telangiectasia. rs3218707 is discussed separately in the catalog as a common SNP investigated in relation to cumulative breast cancer risk, not as the highly disruptive mutation responsible for that condition.
What Research Says About Breast Cancer Risk
Scientific interest in rs3218707 comes from studies examining whether combinations of genetic markers can contribute to breast cancer susceptibility. The catalog places this variant in the trait category and assigns moderate evidence strength. It describes rs3218707 as one of several SNPs that may contribute to a cumulative increased risk, rather than as a stand-alone explanation for breast cancer. This distinction matters. A statistical association means that a genotype occurred more or less often in people with a trait in a study population; it does not prove that the variant directly causes the trait. Breast cancer risk also reflects family history, other genetic markers, environmental exposures, lifestyle factors, and chance. Evidence can be refined as studies become larger or include more diverse populations. Accordingly, a result for rs3218707 should be understood as one possible piece of a broader risk picture, not as a diagnosis, a certainty, or a substitute for clinical assessment.
How Common It Is and How to Use the Result
The catalog lists a Global Minor Allele Frequency, or GMAF, of approximately 0.012 for rs3218707. In general terms, that indicates that the cataloged minor allele is relatively uncommon overall. Frequencies can differ between ancestral populations, and a global estimate does not describe every population equally. The supplied record does not provide a detailed ancestry-specific frequency table, so the exact prevalence of each genotype should not be inferred from the GMAF alone. A consumer genetic report may show CC, CG, or GG. In the catalog framing, CC is the most common and neutral genotype, while CG and GG are classified as higher-attention. These labels do not mean that a person will or will not develop cancer. They also do not, by themselves, determine medical screening or treatment. Readers can use the result as a prompt to review the report with a qualified clinician or genetic counselor alongside family history and other relevant information, but should not change care based solely on this SNP.
How common is this variant?
The catalog lists a Global Minor Allele Frequency (GMAF) of approximately 0.012, indicating that the minor allele is relatively uncommon overall. Frequencies may differ across ancestral populations, and the supplied record does not provide detailed ancestry-specific genotype frequencies.
Frequently asked questions
Does an ATM rs3218707 higher-attention genotype mean I will get breast cancer?
No. The variant has been studied as part of a cumulative statistical association with breast cancer risk, not as a diagnosis or certainty. Breast cancer risk reflects many genetic and non-genetic factors, and most individual outcomes cannot be determined from this SNP alone.
Should I change my breast cancer screening because of rs3218707?
Do not change medical care based solely on this SNP result. Share the report with a qualified clinician or genetic counselor, who can consider family history and other relevant information when interpreting its significance.
Is rs3218707 the ATM mutation that causes ataxia-telangiectasia?
No. Ataxia-telangiectasia is a rare, severe recessive condition caused by two highly disruptive, pathogenic ATM mutations. The supplied catalog describes rs3218707 as a common SNP studied in relation to cumulative breast cancer risk, not as the mutation responsible for that condition.
Why does my ATM rs3218707 result show two letters?
Most people have two copies of the ATM gene, so a report can display the two alleles observed at this DNA position. The supplied catalog lists CC, CG, and GG as the possible common genotype combinations.
Where can I get help interpreting this result?
A qualified clinician or genetic counselor can place the result in the context of your family health history and other risk information. A single SNP result should not be interpreted as a diagnosis or used as the sole basis for medical decisions.
Sources & further reading
Educational information only, last refreshed 9/21/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Intronic variant in the ATM gene associated with glycemic response to metformin in patients with type 2 diabetes.
Missense variant (p.Asp1853Asn) in ATM associated with altered DNA damage response, radiation-induced toxicity, and chemotherapeutic sensitivity.
This variant in the ATM gene is a clinically significant marker often studied in the context of DNA repair and cancer susceptibility.
This variant in the ATM gene is one of several identified as contributing to minor, independent risks for specific health conditions.