Is BRCA1 p.Thr1620= (c.4860T>C) pathogenic?

BRCA1 p.Thr1620= (c.4860T>C) is classified Likely benign in BRCA1 (ClinVar, Expert panel, 8 submitters; last evaluated 2017-06-29). Very rare (popmax 0.00246%, nfe); Associated with breast-ovarian cancer, familial, susceptibility to, 1.

What condition is associated with BRCA1 p.Thr1620= (c.4860T>C)?

BRCA1 p.Thr1620= (c.4860T>C) is associated with breast-ovarian cancer, familial, susceptibility to, 1, hereditary breast ovarian cancer syndrome, hereditary neoplastic syndrome (ClinVar).

How common is BRCA1 p.Thr1620= (c.4860T>C) in the general population?

BRCA1 p.Thr1620= (c.4860T>C) is very rare (popmax 0.00246%, nfe) (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.Thr1620=

c.4860T>C · rs750938749 · VCV240808

Likely benign Expert panel

Classification

Likely benign

ClinVar

Review

Expert panel ★★★☆

ClinVar · 8 submitters

gnomAD v4.1

Rare

very rare (popmax 0.00246%, nfe)

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
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 2.1	GERP 2.2, phastCons 0.001
Overall
CADD	1.826	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00246% European (non-Finnish) · 29/1,180,026 alleles

Filtering AF 0.00172% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00149%

Overall 0.00205% 30/1,461,872 alleles · very rare

Ancestry group	Frequency	1 in
European (non-Finnish)grpmax	0.00246%	40,691
African / African-American	0.00133%	75,032

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.Thr1620=
Coding: c.4860T>C
MANE Select: NM_007294
dbSNP: rs750938749
Type: single nucleotide variant
Location: chr17:43071054 (GRCh38)
Gene constraint: LOEUF 0.885 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 41.99 · 33 PDB
Residue 1620: a UniProt-annotated variant site (in fancs); a UniProt-annotated variant site (in)

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.Thr1620Ile Uncertain significance ★★ ⚠ same residue
BRCA1 p.Thr1620Ala Conflicting classifications of pathogenicity ★ ⚠ same residue
BRCA1 p.Thr1620fs 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
BRCA1 c.212+3A>G 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-thr1620 (accessed [today's date]).

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