TOP3B

Chr 22

DNA topoisomerase III beta

Also known as: TOP3B1

NCBI Gene: 8940ENSG00000100038UniProt: O95985

This gene encodes a DNA topoisomerase, an enzyme that controls and alters the topologic states of DNA during transcription. This enzyme catalyzes the transient breaking and rejoining of a single strand of DNA which allows the strands to pass through one another, thus relaxing the supercoils and altering the topology of DNA. The enzyme interacts with DNA helicase SGS1 and plays a role in DNA recombination, cellular aging and maintenance of genome stability. Low expression of this gene may be related to higher survival rates in breast cancer patients. This gene has a pseudogene on chromosome 22. Alternate splicing results in multiple transcript variants. Additional alternatively spliced transcript variants of this gene have been described, but their full-length nature is not known. [provided by RefSeq, Aug 2013]

ResearchGenerating clinical summary…

Clinical highlights

Interpreting a novel variant
This gene is strongly intolerant of loss-of-function variation in the population, so LoF variants warrant close attention. No curated mechanism annotation is available — see the mechanism card for the computational prediction and its caveats.Based on population constraint only.
0
Active trials
17
Pubs (1 yr)
—
P/LP submissions
—
P/LP missense
0.54
LOEUF
DN
Mechanism· predicted
Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
Moderate LoF intolerance
LoF Constraint?
0.54LOEUF
pLI 0.000
Z-score 3.88
OE 0.34 (0.23–0.54)
Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint?
2.23Z-score
OE missense 0.73 (0.67–0.79)
381 obs / 524.5 exp
Mild constraint

Moderately missense-constrained (top ~2.5%)

Observed / Expected Ratios?
LoF OE?0.34 (0.23–0.54)
0≤0.351.4
Missense OE?0.73 (0.67–0.79)
0≤0.61.4
Synonymous OE?0.99
0≤1.21.6
LoF obs/exp: 14 / 40.7Missense obs/exp: 381 / 524.5Syn Z: 0.14

ClinVar Variant Classifications

0 submitted variants in ClinVar

ClinVar

Protein Context — Lollipop Plot

TOP3B · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov

No active trials found for this gene.

Search ClinicalTrials.gov →

External Resources

Links to major genomics databases and tools

Franklin by Genoox
AI-powered variant curation and clinical analysis
DECIPHER
Genomic variants and phenotypes in rare disease patients