Is BRCA1 c.134+296C>T pathogenic?

BRCA1 c.134+296C>T is classified Benign in BRCA1 (ClinVar, Expert panel, 1 submitter; last evaluated 2015-01-12). Rare (popmax 0.111%, afr); Associated with breast-ovarian cancer, familial, susceptibility to, 1.

What condition is associated with BRCA1 c.134+296C>T?

BRCA1 c.134+296C>T is associated with breast-ovarian cancer, familial, susceptibility to, 1 (ClinVar).

How common is BRCA1 c.134+296C>T in the general population?

BRCA1 c.134+296C>T is rare (popmax 0.111%, afr) (gnomAD).

How is Hereditary breast and/or ovarian cancer syndrome inherited?

Typically Autosomal dominant (Orphanet). A genetic counselor can assess individual risk for a family.

BRCA1 c.134+296C>T

rs139405471 · VCV209533

Benign Expert panel

Classification

Benign

ClinVar

Review

Expert panel ★★★☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

rare (popmax 0.111%, afr)

Conditions

breast-ovarian cancer, familial, susceptibility to, 1

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
Splice region	donor +296	deep intronic (+296 nt into the intron)
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.28	GERP -0.44
Non-coding constraint	Z -0.09	1 kb window · o/e 1.01 · regional · uncalibrated
Overall
CADD	1.356	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.111% African / African-American · 46/41,404 alleles

Filtering AF 0.0856% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0766%

Overall 0.0329% 50/151,898 alleles · rare

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.111%	900
Remaining individualsnot grpmax-eligible	0.0954%	1,048
Admixed American	0.0131%	7,623

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: BRCA1
Coding: c.134+296C>T
MANE Select: NM_007294
dbSNP: rs139405471
Type: single nucleotide variant
Location: chr17:43115430 (GRCh38)
Gene constraint: LOEUF 0.885 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 41.99 · 33 PDB

Full BRCA1 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

breast-ovarian cancer, familial, susceptibility to, 1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Hereditary breast and/or ovarian cancer syndrome (Orphanet):

Inheritance: Autosomal dominant
Onset: Adult, Elderly

Similar variants

BRCA1 c.134+3A>T Likely pathogenic ★★★ same condition
BRCA1 c.135-1G>T Pathogenic ★★★ same condition
BRCA1 c.212+1G>A Pathogenic ★★★ same condition
BRCA1 c.212+1G>T Pathogenic ★★★ same condition
BRCA1 c.212+3A>G Pathogenic ★★★ same condition
BRCA1 c.213-12A>G Pathogenic ★★★ same condition
BRCA1 c.213-15A>G Likely pathogenic ★★★ same condition
BRCA1 c.302-1G>C Pathogenic ★★★ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/brca1-c-134-plus-296c-t (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown