TOP3A p.Cys296=
c.888C>T · rs1374809736 · VCV1571894
Likely benign
Single submitter
Classification
Likely benign
ClinVar
Review
Single submitter ★☆☆☆
ClinVar · 1 submitter
gnomAD v4.1
Rare
very rare (popmax 0.00167%, amr)
Computational evidence
| Protein change | ||
| Missense predictors do not apply to this variant type; conservation carries the signal. | ||
| REVEL | 0.093 | moderately benign-leaning |
|---|---|---|
| Splicing | ||
| SpliceAI | — | not assessed · no allele here is in the release |
| Constraint at this position | ||
| Conservation | phyloP 2.6 | GERP -0.59, phastCons 1 |
| Overall | ||
| CADD | 9.19 | PHRED · no single calibrated threshold — expert panels disagree |
Population frequency
gnomAD v4.1 · exomes + genomes
Grpmax group
0.00167%
Admixed American · 1/60,002 alleles
Filtering AF
2.8e-05%
ClinGen BA1/BS1 input
FAF95, joint · FAF99 1.1e-05%
Overall
0.000248%
4/1,614,048 alleles · very rare
exomes 3/1,461,862 · genomes 1/152,186 · joint denominator
| Ancestry group | Frequency | 1 in |
|---|---|---|
| Admixed Americangrpmax | 0.00167% | 60,002 |
| Finnishnot grpmax-eligible | 0.00156% | 64,032 |
| European (non-Finnish) | 0.000169% | 590,016 |
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
- TOP3A
- Protein
- p.Cys296=
- Coding
- c.888C>T
- MANE Select
- NM_004618
- dbSNP
- rs1374809736
- Type
- single nucleotide variant
- Location
- chr17:18301912 (GRCh38)
- Gene constraint
- LOEUF 0.737 · pLI <0.01 (gnomAD)
- Structure
- AlphaFold pLDDT 84.14 · 2 PDB
- Residue 296
- the topo ia-type catalytic domain; a UniProt-annotated variant site (in peob5); an α-helix
Similar variants
- TOP3A p.Cys296Ser Uncertain significance ★ same residue
- TOP3A c.990+1G>T Likely pathogenic ★★ same type
- TOP3A p.Arg135Ter Pathogenic/Likely pathogenic ★★ same type
- TOP3A p.Arg177Ter Pathogenic/Likely pathogenic ★★ same type
- TOP3A p.Arg338Ter Pathogenic/Likely pathogenic ★★ same type
- TOP3A p.Ala622Thr Uncertain significance ★★ ⚠ same type
- TOP3A p.Ala642Val Uncertain significance ★★ ⚠ same type
- TOP3A p.Ala941Thr Uncertain significance ★★ ⚠ same type
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/top3a-p-cys296 (accessed [today's date]).
Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown