Is BRCA1 p.Ser1377= (c.4131C>T) pathogenic?

BRCA1 p.Ser1377= (c.4131C>T) is classified Likely benign in BRCA1 (ClinVar, Expert panel, 6 submitters; last evaluated 2017-06-29). Very rare (popmax 0.00334%, amr); Associated with breast-ovarian cancer, familial, susceptibility to, 1.

What condition is associated with BRCA1 p.Ser1377= (c.4131C>T)?

BRCA1 p.Ser1377= (c.4131C>T) is associated with breast-ovarian cancer, familial, susceptibility to, 1, hereditary breast ovarian cancer syndrome, hereditary neoplastic syndrome (ClinVar).

How common is BRCA1 p.Ser1377= (c.4131C>T) in the general population?

BRCA1 p.Ser1377= (c.4131C>T) is very rare (popmax 0.00334%, amr) (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 p.Ser1377=

c.4131C>T · rs80356871 · VCV184408

Likely benign Expert panel

Classification

Likely benign

ClinVar

Review

Expert panel ★★★☆

ClinVar · 6 submitters

gnomAD v4.1

Rare

very rare (popmax 0.00334%, amr)

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.
REVEL	0.021	moderately benign-leaning
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 1.8	GERP -2, phastCons 0.028
Overall
CADD	7.168	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00334% Admixed American · 2/59,838 alleles

Filtering AF 0.000554% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000208%

Overall 0.000685% 10/1,460,588 alleles · very rare

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.00334%	29,919
African / African-American	0.00133%	75,028
European (non-Finnish)	0.000593%	168,508

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
Protein: p.Ser1377=
Coding: c.4131C>T
MANE Select: NM_007294
dbSNP: rs80356871
Type: single nucleotide variant
Location: chr17:43090998 (GRCh38)
Gene constraint: LOEUF 0.885 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 41.99 · 33 PDB
Residue 1377: a UniProt-annotated variant site (in fancs); the 'disordered' region

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

Also linked: hereditary breast ovarian cancer syndrome hereditary neoplastic syndrome

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

Inheritance: Autosomal dominant
Onset: Adult, Elderly

Similar variants

BRCA1 p.Ser1377Arg Uncertain significance ★★ ⚠ same residue
BRCA1 p.Ser1377Gly Uncertain significance ★★ ⚠ same residue
BRCA1 p.Ser1377Asn Conflicting classifications of pathogenicity ★ ⚠ same residue
BRCA1 p.Ser1377fs Pathogenic ★★★ same residue
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

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-p-ser1377 (accessed [today's date]).

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