ATM HEREDITARY CANCER RISK

ATM Hereditary Cancer Risk — a DNA damage repair gene on the ACMG secondary findings list, conferring elevated breast, pancreatic, and prostate cancer risk and directly influencing sensitivity to PARP inhibitors and platinum chemotherapy.

Whole genome sequencing reads all 66 ATM exons simultaneously — the only way to reliably detect the full spectrum of ATM variants, including the large deletions and deep intronic variants that standard cancer panels systematically undercount.

About this condition

ATM Hereditary Cancer Risk

ATM (ataxia-telangiectasia mutated) encodes a serine-threonine protein kinase that is a master regulator of the DNA double-strand break response. Biallelic ATM pathogenic variants cause ataxia-telangiectasia (AT), a rare severe multisystem disorder characterized by cerebellar ataxia, oculomotor apraxia, immunodeficiency, telangiectasias, and markedly elevated cancer risk — particularly lymphoid malignancies. Heterozygous ATM pathogenic variants, present in approximately 0.5-1% of the general population, are associated with a less severe but clinically significant cancer predisposition syndrome that has been precisely characterized only in recent years through large-scale population genomics studies.

ATM heterozygous carriers have an estimated 20-25% lifetime breast cancer risk (compared to approximately 12% population average), with NCCN guidelines recommending enhanced breast cancer surveillance (annual breast MRI from age 40) for affected individuals. ATM carriers also face elevated pancreatic cancer risk (approximately 5-7% lifetime, compared to ~1.5% population average), elevated prostate cancer risk in males (particularly high-grade disease), and potentially elevated colorectal and ovarian cancer risk. ATM is now included in the ACMG SF v3.2 secondary findings list, reflecting consensus that actionable clinical management changes are warranted for identified carriers.

ATM has direct implications beyond cancer risk stratification — it is a theranostic biomarker. Cancers arising in ATM-deficient patients may be particularly sensitive to agents that exploit DNA repair pathway deficiencies: PARP inhibitors, platinum chemotherapy, and ATM kinase inhibitors currently in clinical trial. Germline ATM status now informs cancer treatment decisions — olaparib is FDA-approved for metastatic castration-resistant prostate cancer in patients with ATM pathogenic variants, and clinical trials are evaluating PARP inhibitor combinations for pancreatic cancer in ATM carriers. This dual role — hereditary cancer risk management and treatment selection — makes complete ATM genotyping increasingly urgent.

Gene locus: ATM (11q22.3)

ATM is a 66-exon gene with over 3,000 documented variants. Many reported ATM variants are variants of uncertain significance — complete gene sequencing with functional context is needed to interpret them properly.

ATM has 66 exons and thousands of variants — limited panels frequently miss rare pathogenic alleles

The ATM gene is one of the largest cancer predisposition genes, spanning 150 kilobases with 66 coding exons. Over 3,000 ATM sequence variants have been documented, the majority of which are missense variants of uncertain significance. Truncating variants (nonsense, frameshift, essential splice site) are definitively classified as pathogenic when identified. Large ATM deletions — detectable only by copy number variant analysis — account for a meaningful fraction of ATM pathogenic variants in familial cancer cases and are not reliably detected by standard panel sequencing. Whole genome sequencing covers all 66 exons with simultaneous copy number variant analysis, resolving the full ATM variant spectrum.

Germline ATM status now determines PARP inhibitor eligibility in prostate cancer

The FDA approved olaparib (Lynparza) and rucaparib (Rubraca) for metastatic castration-resistant prostate cancer in patients with ATM pathogenic variants, alongside BRCA1/2 variants. This approval makes germline ATM testing directly treatment-enabling for prostate cancer patients — a patient who tests ATM-positive on a complete gene analysis may qualify for PARP inhibitor monotherapy rather than chemotherapy. Clinical trials are also evaluating PARP inhibitors specifically in germline ATM-positive pancreatic cancer (a setting with very few approved options). Complete ATM genotyping — not a partial panel that may miss rare truncating or structural variants — is required for accurate somatic vs. germline status determination and treatment eligibility assessment.

ATM Hereditary Cancer Risk — a DNA damage repair gene on the ACMG secondary findings list, conferring elevated breast, pancreatic, and prostate cancer risk and directly influencing sensitivity to PARP inhibitors and platinum chemotherapy.