# NM_000059.4(BRCA2):c.7977A>G (p.Arg2659=)

https://sugi.bio/variant/brca2-p-arg2659

## Summary

**BRCA2 p.Arg2659= (c.7977A>G)** is classified **Uncertain significance** in BRCA2 (ClinVar, Single submitter, 1 submitter; last evaluated 2024-02-29). Absent from gnomAD v4.1.

**At a glance:** Uncertain significance · review: Single submitter · 1 submitter · absent from gnomAD v4.1

## For patients & families {#patients}

This is a change in the BRCA2 gene that is currently of uncertain significance — a definitive interpretation has not yet been established, submitted by 1 submitter.

*Reference information, not medical advice, and not a prediction for any individual. A genetic counselor or clinician can interpret what it means for you and your family.*

**Support & next steps:** [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [BRCA2](https://sugi.bio/atlas/gene/BRCA2/) |
| Protein change (HGVS p.) | p.Arg2659= |
| Coding change (HGVS c.) | c.7977A>G |
| MANE Select transcript | [NM_000059](https://www.ncbi.nlm.nih.gov/nuccore/NM_000059) |
| Variant type | single nucleotide variant |
| Location | chr13:32363179-32363179 (GRCh38) |
| ClinVar | [VCV3572367](https://www.ncbi.nlm.nih.gov/clinvar/variation/3572367/) |

**All HGVS expressions:** `LRG_293:g.52700A>G`, `LRG_293t1:c.7977A>G`, `NC_000013.10:g.32937316A>G`, `NC_000013.11:g.32363179A>G`, `NG_012772.3:g.52700A>G`, `NM_000059.4:c.7977A>G`, `NM_001406719.1:c.7881A>G`, `NM_001406720.1:c.7977A>G`, `NM_001406721.1:c.3045A>G`, `NM_001406722.1:c.1560A>G`, `NM_001432077.1:c.7977A>G`, `NR_176251.1:n.8176A>G`

## Computational & population evidence {#evidence}

**Concordance:** Mixed / partial computational evidence (see below).

- **Missense predictors (AlphaMissense/REVEL/SaProt) do not apply** to this variant type — they score amino-acid substitutions only. For non-missense variants the computational signal comes from conservation (below), not from a missing predictor score.
- Conservation: phyloP 1.746, GERP -1.49, phastCons 1 — weakly conserved position
- CADD: **PHRED 6.239**. No single ClinGen-calibrated threshold exists and the expert panels that use CADD disagree — GUCY2D/AIPL1 require ≥ 20.0 for an untranslated-region variant, ABCA4 ≥ 28.1 for a synonymous or indel variant, the Pulmonary Hypertension panel imports Pejaver 2022's missense-calibrated numbers, and the Antibody Deficiencies panel declines CADD entirely for PIK3CD. CADD v1.7 also incorporates Zoonomia phyloP, so it partly re-expresses the conservation above. *Descriptive; no threshold applied.*
- SpliceAI: **not assessed** — no allele at this position is in our SpliceAI release, either because it lies outside the scored MANE transcript scope or because every allele is below Δ0.2. We cannot tell which, so this claims neither; absence is not evidence against a splicing effect.
- Population frequency: **absent from gnomAD v4.1** — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

*Computational predictors are not independent (ClinGen Variant Classification guidance): AlphaMissense (Cheng et al. 2023) carries the ACMG weight for missense and conservation (phyloP/GERP/phastCons) for non-missense; REVEL (Pejaver-2022 calibrated strength bands) and SaProt (Su et al. 2023, structure-aware, ClinVar-independent protein language model, raw LLR) are shown as orthogonal agreement signals, not additive. For frequency, the gnomAD v4.1 grpmax filtering allele frequency (FAF95) is ClinGen's designated BA1/BS1 input (gnomAD v4 guidance v3.0, June 2025); BA1/BS1 thresholds are disease-specific, not a blanket 5%. Predictions, not a clinical determination.*

## Gene constraint & dosage {#gene-context}

**BRCA2** population constraint: LOEUF 0.803, pLI 6.5274e-44, missense-Z 1.0218; ClinGen dosage — haploinsufficiency 3, triplosensitivity 0 (0–3 scale). *Lower LOEUF and higher pLI indicate a gene that tolerates loss-of-function poorly; ClinGen dosage is the curated haploinsufficiency call.*

Curated gene–disease validity (ClinGen):

- **Fanconi anemia complementation group D1** — Definitive (AR)
- **BRCA2-related cancer predisposition** — Definitive (AD)

## Protein context {#protein}

Residue **2659** lies in a UniProt-annotated variant site (in bc; uncertain significance); the 'interaction with sem1' region.

**14 experimental structure(s)** (PDB): [1N0W](https://www.rcsb.org/structure/1N0W), [3EU7](https://www.rcsb.org/structure/3EU7), [6GY2](https://www.rcsb.org/structure/6GY2), [6HQU](https://www.rcsb.org/structure/6HQU), [7BDX](https://www.rcsb.org/structure/7BDX), [7LDG](https://www.rcsb.org/structure/7LDG) — incl. mutant structure 6HQU.

## What this gene does {#gene-function}

*Describes the biological roles of BRCA2 (the gene this variant disrupts) — not effects measured for this specific variant. A damaging variant is expected to affect these functions and pathways; the degree depends on the variant.*

**How this variant is thought to act:** BRCA2's established molecular role includes protease binding. p.Arg2659= falls in the interaction with sem1 region. In Reactome, BRCA2 is annotated in disease pathway(s) including **Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA1 binding function**, **Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA2/RAD51/RAD51C binding function**.

**Disease mechanism (Reactome):** BRCA2 loss or alteration is curated in [Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA1 binding function](https://reactome.org/content/detail/R-HSA-9704331), [Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA2/RAD51/RAD51C binding function](https://reactome.org/content/detail/R-HSA-9704646), [Defective homologous recombination repair (HRR) due to BRCA1 loss of function](https://reactome.org/content/detail/R-HSA-9701192).

### Pathways affected {#pathways}

BRCA2 participates in **14 Reactome pathways** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| ⚕ [Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA1 binding function](https://reactome.org/content/detail/R-HSA-9704331) | curated |
| ⚕ [Defective HDR through Homologous Recombination Repair (HRR) due to PALB2 loss of BRCA2/RAD51/RAD51C binding function](https://reactome.org/content/detail/R-HSA-9704646) | curated |
| ⚕ [Defective homologous recombination repair (HRR) due to BRCA1 loss of function](https://reactome.org/content/detail/R-HSA-9701192) | curated |
| ⚕ [Impaired BRCA2 binding to PALB2](https://reactome.org/content/detail/R-HSA-9709603) | curated |
| ⚕ [Impaired BRCA2 binding to RAD51](https://reactome.org/content/detail/R-HSA-9709570) | curated |
| ⚕ [Impaired BRCA2 binding to SEM1 (DSS1)](https://reactome.org/content/detail/R-HSA-9763198) | curated |
| ⚕ [Impaired BRCA2 translocation to the nucleus](https://reactome.org/content/detail/R-HSA-9709275) | curated |
| [HDR through Homologous Recombination (HRR)](https://reactome.org/content/detail/R-HSA-5685942) | curated |
| [HDR through MMEJ (alt-NHEJ)](https://reactome.org/content/detail/R-HSA-5685939) | curated |
| [Homologous DNA Pairing and Strand Exchange](https://reactome.org/content/detail/R-HSA-5693579) | curated |
| [Presynaptic phase of homologous DNA pairing and strand exchange](https://reactome.org/content/detail/R-HSA-5693616) | curated |
| [Resolution of D-loop Structures through Holliday Junction Intermediates](https://reactome.org/content/detail/R-HSA-5693568) | curated |
| [Resolution of D-loop Structures through Synthesis-Dependent Strand Annealing (SDSA)](https://reactome.org/content/detail/R-HSA-5693554) | curated |
| [Meiotic recombination](https://reactome.org/content/detail/R-HSA-912446) | electronic |

### Molecular function & processes (GO — experimentally supported) {#go}

**Molecular function:** protease binding, single-stranded DNA binding, histone H3 acetyltransferase activity, histone H4 acetyltransferase activity, identical protein binding, gamma-tubulin binding.

**Biological process:** double-strand break repair via homologous recombination, nucleotide-excision repair, double-strand break repair, negative regulation of mammary gland epithelial cell proliferation, positive regulation of DNA-templated transcription, centrosome duplication.

## Clinical significance {#significance}

**Uncertain significance** — review status Single submitter *(criteria provided, single submitter)*, last evaluated 2024-02-29.

**Submitter consensus:** unanimous (1/1 Uncertain significance).

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Quest Diagnostics Nichols Institute San Juan Capistrano | Uncertain significance | criteria provided, single submitter | clinical testing | 2024-02-29 |

**Reported phenotype names (ClinVar):** not provided, none provided, RECLASSIFIED - ADRA2C POLYMORPHISM, RECLASSIFIED - ADRB1 POLYMORPHISM.

## Same-residue context {#hotspot}

Residue **2659** carries **4 other pathogenic ClinVar variants** — a recurrently-mutated position: [BRCA2 p.Arg2659Ser](/variant/brca2-p-arg2659ser), [BRCA2 p.Arg2659Gly](/variant/brca2-p-arg2659gly), [BRCA2 p.Arg2659Lys](/variant/brca2-p-arg2659lys), [BRCA2 p.Arg2659Thr](/variant/brca2-p-arg2659thr). *Positional co-occurrence of independent ClinVar records, not functional proof.*

## Similar variants {#similar}

Related BRCA2 variant pages (same residue, condition, or type): [BRCA2 p.Arg2659Gly](/variant/brca2-p-arg2659gly), [BRCA2 p.Arg2659Thr](/variant/brca2-p-arg2659thr), [BRCA2 p.Arg2659Lys](/variant/brca2-p-arg2659lys), [BRCA2 p.Arg2659Ile](/variant/brca2-p-arg2659ile), [BRCA2 p.Arg2659Ser](/variant/brca2-p-arg2659ser), [BRCA2 c.316+1G>T](/variant/brca2-c-316-plus-1g-t), [BRCA2 c.316+2T>C](/variant/brca2-c-316-plus-2t-c), [BRCA2 c.316+5G>A](/variant/brca2-c-316-plus-5g-a).

### Data sources & attribution {#sources}

ClinVar (NCBI — public domain, built 2026-10-11); gnomAD v4.1 (Broad Institute, built 2026-10-06); AlphaMissense (Cheng et al. 2023, © Google DeepMind — CC BY 4.0, built 2026-01-27); REVEL (Ioannidis et al. 2016 — ODbL, built 2026-07-13); SaProt (Su et al. 2023 — MIT, built 2026-07-14); SpliceAI (Illumina — free for non-commercial use, built 2026-10-13); CADD (Rentzsch et al. 2019, University of Washington — free for non-commercial use, built 2026-10-10); Conservation (phyloP/phastCons/GERP) (UCSC hg38 470-way mammal (Hiller Lab) + Ensembl Compara, built 2026-07-12); gnomAD Non-coding Constraint (Gnocchi) (Chen et al. 2024, Broad Institute — CC0, built 2026-10-11); gnomAD Regional Missense Constraint (Broad Institute — CC0, built 2026-10-13); Pangolin (Zeng & Li 2022 — CC BY 4.0, built 2026-10-11); Repeat regions (UCSC — RepeatMasker, TRF, segmental duplications, built 2026-10-11); ClinGen (ClinGen, built 2026-09-22); UniProt (CC BY 4.0); Reactome / GO (CC BY 4.0, built 2026-09-23); MaveDB (per-record license, built 2026-10-11); CIViC (CC0, built 2026-09-22); Orphanet (Orphanet, built 2026-06-12)

*Primary record: NCBI ClinVar (variation 3572367). Classifications reflect these databases as of the page's build date and may change. Free reference use — not medical advice; consult the primary submitters and a clinician.*