Breast Armor DNA

Breast Armor DNA — Hereditary Breast Cancer Multi-Gene Panel + Polygenic Risk Score (SGD 899)

Breast Armor DNA is EMIS+'s most comprehensive hereditary breast cancer genetic risk assessment, combining extended multi-gene panel sequencing with a validated polygenic risk score (PRS) to deliver complete, quantified lifetime and 10-year breast cancer risk stratification. Available at emis.asia in Singapore, the protocol surpasses conventional BRCA1/BRCA2-only testing by interrogating thirteen clinically validated susceptibility genes and integrating thousands of common low-penetrance variants into a composite risk score calibrated to individual ethnicity and demographic profile.

Gene Panel Architecture: The extended panel sequences BRCA1, BRCA2 (high-penetrance; cumulative lifetime breast cancer risk 50–85%), PALB2 (moderate-high penetrance; lifetime risk 33–58%, NEJM 2014), CHEK2 (moderate penetrance; 1100delC variant, lifetime risk 20–25%), ATM (moderate penetrance, lifetime risk 15–25%), TP53 (Li-Fraumeni syndrome; near-100% lifetime cancer penetrance), PTEN (Cowden syndrome; lifetime breast risk 25–50%), CDH1 (hereditary diffuse gastric cancer syndrome; lobular breast risk 39–52%), RAD51C and RAD51D (moderate-penetrance; BRCA-pathway DNA repair; ovarian cancer co-risk), BARD1, and BRIP1. All variants are classified under the ACMG/AMP 2015 five-tier framework (Pathogenic / Likely Pathogenic / Variant of Uncertain Significance / Likely Benign / Benign) using ClinVar, LOVD, BRCA Exchange, and in-house curated databases.

Polygenic Risk Score (PRS313): PRS313 — a validated 313-SNP breast cancer polygenic risk score developed from the Breast Cancer Association Consortium (BCAC) GWAS — is genotyped via genome-wide SNP chip and calibrated to East Asian reference populations. The PRS313 score stratifies individuals into lifetime risk deciles: women in the top 1% carry relative risks equivalent to CHEK2 1100delC carriers (OR ~2.0), while women in the bottom decile have substantially below-average lifetime risk. Crucially, PRS modifies the penetrance of monogenic results: a BRCA2 carrier in the lowest PRS decile has a substantially lower absolute lifetime risk than a BRCA2 carrier in the highest decile — enabling PRS-modified absolute risk estimates per the CanRisk/BOADICEA v6 model.

BOADICEA Lifetime Risk Calculation: All results are processed through the BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) v6 model — the global clinical standard endorsed by NICE (UK), NCCN, and the Singapore MOH — which integrates monogenic findings, PRS313 score, family history, hormonal/reproductive factors, mammographic density (where available), and lifestyle parameters to compute individualised 10-year and lifetime absolute breast and ovarian cancer risk percentages. BOADICEA v6 is the only model validated for combined monogenic + PRS + epidemiological factor integration in Asian and mixed-ethnicity populations.

Variant Reporting and Clinical Interpretation: All sequencing is performed by next-generation sequencing (NGS) using the Illumina NovaSeq platform with mean depth ≥500× for exon regions and ≥50× for intronic splice regions. Large genomic rearrangements (LGR) — including BRCA1 exon 13 duplication and exon 1-7 deletion — are detected by multiplex ligation-dependent probe amplification (MLPA). Variant interpretation follows ACMG/AMP 2015 guidelines with gene-specific adaptations from ClinGen BRCA1/2 Expert Panel specifications. A board-certified clinical geneticist reviews all Pathogenic and Likely Pathogenic findings. Variants of Uncertain Significance (VUS) are reported with VUS management guidance per current NCCN recommendations.

Cascade Testing and Surveillance Protocols: Breast Armor DNA includes carrier cascade testing guidance, identifying which first-degree and second-degree relatives should undergo targeted variant testing. Risk-stratified surveillance recommendations are calibrated to the BOADICEA lifetime risk output: individuals with lifetime risk ≥30% receive annual breast MRI + mammography protocols per NICE CG164 and NCCN Genetic/Familial High-Risk guidelines; those with lifetime risk 20–29% receive mammography with supplemental ultrasound; those with lifetime risk <20% receive standard population-based screening. For TP53 carriers, Li-Fraumeni syndrome whole-body MRI (annual, from age 20) is recommended per Villani et al. (Lancet Oncology 2016).

Q1: What are the limitations of BRCA1/2-only testing, and why does the Breast Armor DNA extended panel improve clinical utility?

Standard BRCA1/2 testing identifies pathogenic variants in approximately 5–10% of breast cancer cases and misses the hereditary component attributable to eleven other validated susceptibility genes. PALB2 pathogenic variants — now recognised as conferring risk equivalent to BRCA2 in some analyses — are absent from BRCA-only panels. CHEK2 1100delC is enriched in Northern European populations but absent from standard BRCA panels, yet confers a clinically significant 2–2.5× relative risk of breast cancer. ATM heterozygotes, constituting approximately 0.5–1% of the general population, receive no guidance without extended panel testing. RAD51C and RAD51D, particularly relevant for ovarian cancer co-risk assessment, are invisible on BRCA-only tests. The Breast Armor DNA extended panel captures all NCCN-recommended hereditary breast cancer genes, ensuring that women with moderate-penetrance mutations who would otherwise test negative on a BRCA-only assay receive appropriate surveillance intensification and cascade testing guidance.

Q2: How does the PRS313 polygenic risk score modify the clinical interpretation of a monogenic finding — for example, a BRCA2 pathogenic variant?

The interaction between monogenic high-penetrance mutations and the polygenic background is substantial and clinically actionable. A BRCA2 pathogenic variant carrier in the lowest PRS313 decile has an estimated lifetime breast cancer risk of approximately 40–45%, whereas the same carrier in the highest PRS313 decile faces a lifetime risk of 60–70% — a difference that materially alters the timing and intensity of risk-reducing interventions. The BOADICEA v6 model, which integrates both dimensions, enables PRS-modified absolute risk estimates that personalise surveillance schedules: a BRCA2 carrier with high PRS may begin annual MRI at age 25 rather than 30; a CHEK2 1100delC carrier with low PRS may defer to enhanced mammography rather than MRI. Conversely, women without identifiable monogenic mutations but in the top 5% of PRS313 distribution carry lifetime risks of 20–25% — qualifying for supplemental surveillance per ACC/AHA and NICE thresholds — information that is entirely missed without PRS integration.

Q3: What is the clinical management protocol for a woman who receives a Variant of Uncertain Significance (VUS) in BRCA1 or PALB2?

A Variant of Uncertain Significance (VUS) indicates a genetic change for which current evidence is insufficient to classify definitively as disease-causing or benign — it does not equal a positive result for clinical management purposes. Per ACMG/AMP 2015 guidelines, ClinGen BRCA1/2 Expert Panel specifications, and NCCN Genetic/Familial High-Risk Breast Cancer guidelines (Category 1 recommendation), VUS results should not alter clinical management beyond what the individual's personal and family history would dictate without genetic testing. Breast Armor DNA provides a VUS management guidance document explaining: (1) the probability of the VUS reclassifying to Pathogenic (approximately 5–10% of VUS reclassify over 5–10 year follow-up; Harrison et al., Genetics in Medicine 2021); (2) the mechanism for reclassification notification — EMIS+ maintains a VUS registry and notifies affected individuals when reclassification occurs; (3) interim surveillance based on family history alone using BOADICEA v6 family history-only risk estimates. Cascade testing of relatives for VUS is generally discouraged unless family history context provides additional segregation evidence.

Q4: What are the surveillance recommendations stratified by BOADICEA lifetime risk output?

Breast Armor DNA translates BOADICEA v6 absolute lifetime risk into one of four evidence-based surveillance tiers. Population risk (lifetime risk <17%): Standard Singapore national breast screening programme — biennial mammography from age 40–49, annual from 50–69 (Singapore Cancer Registry / MOH guidelines). Moderate risk (lifetime risk 17–29%): Enhanced annual mammography with supplemental breast ultrasound; clinical breast examination annually; consider MRI if mammographic density BI-RADS D (heterogeneously or extremely dense) per ACOG Practice Bulletin 2022. High risk (lifetime risk ≥30% or BRCA1/2 / PALB2 / TP53 / PTEN pathogenic variant): Annual breast MRI (contrast-enhanced, optimally Days 7–14 of menstrual cycle) + annual mammography + clinical breast examination 6-monthly; risk-reducing options discussion (chemoprevention with tamoxifen/raloxifene/exemestane per IBIS-I/II evidence; risk-reducing salpingo-oophorectomy for BRCA1 carriers by age 35–40; risk-reducing mastectomy discussion per individual preference and risk magnitude). TP53 carriers (Li-Fraumeni): Whole-body MRI annually from age 20; brain MRI annually; colonoscopy every 2–5 years; dermatology annually — per Villani et al. Lancet Oncology 2016 LFS surveillance protocol.

Q5: How does Breast Armor DNA inform cascade testing, and what is the recommended protocol for family members?

Cascade testing — the systematic offer of genetic testing to biological relatives of a pathogenic variant carrier — is among the highest-value interventions in hereditary cancer medicine, since each Pathogenic variant identified in a proband implies a 50% probability that first-degree relatives carry the same variant. Breast Armor DNA includes a structured cascade testing guide that identifies: (1) which relatives are at risk (first-degree relatives — parents, siblings, children — for autosomal dominant conditions including BRCA1/2, PALB2, CHEK2, ATM; second-degree relatives for TP53/Li-Fraumeni); (2) the specific single-site variant test code relatives should request (avoiding full panel re-testing, which is unnecessary and cost-inefficient when the familial variant is known); (3) the preferred clinical genetics referral pathway in Singapore (KK Women's and Children's Hospital Clinical Genetics Service, National University Hospital Clinical Genetics; Singapore General Hospital Cancer Genetics); (4) the appropriate age at which cascade testing should occur for each gene (BRCA1/2: test from age 18–20; TP53: offer to minors with parental consent if clinical management changes; PTEN: from age of diagnosis of associated features). Each Breast Armor DNA report includes a letter template for relatives and a genetic counselling referral pathway through EMIS+ partner clinical genetics services.

Regulatory and Methodological Framework: Breast Armor DNA is performed within an ISO 15189:2022-accredited medical genomics laboratory with CAP (College of American Pathologists) external quality assurance. Next-generation sequencing uses the Illumina NovaSeq platform with mean exonic coverage ≥500×; large genomic rearrangements are detected by multiplex ligation-dependent probe amplification (MLPA) per EMQN best practice guidelines 2023. Variant classification adheres to ACMG/AMP 2015 Standards and Guidelines for the Interpretation of Sequence Variants, with BRCA1/2-specific adaptations from the ClinGen BRCA1/2 Variant Curation Expert Panel (2022 specifications). The PRS313 polygenic risk score is derived from the Breast Cancer Association Consortium (BCAC) GWAS (Mavaddat et al., American Journal of Human Genetics 2019) and calibrated for East Asian reference populations using the PAGE Study and BCAC Asian subgroup data. Lifetime and 10-year absolute risk calculation uses BOADICEA (Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm) version 6, validated for combined monogenic + polygenic + epidemiological factor integration in diverse populations (Lee et al., Genetics in Medicine 2019). Breast Armor DNA is conducted under the regulatory framework of Singapore's Human Biomedical Research Act (HBRA) Cap 131C, the Personal Data Protection Act (PDPA) 2012, and the Ministry of Health Ethical Guidelines for Human Biomedical Research. Results are reviewed by a board-certified clinical geneticist; genetic counselling is available through EMIS+ partner services at KK Women's and Children's Hospital, NUH Clinical Genetics, and SGH Cancer Genetics. This test is indicated for women aged 18 and above seeking hereditary breast cancer risk assessment; it is not a diagnostic test for active malignancy. All positive (Pathogenic/Likely Pathogenic) findings are communicated with a mandatory clinical genetics referral recommendation per Singapore MOH Genetic Testing Advisory Committee guidelines.