Genetic Variant TOP3A:p.Gly975Arg (chr17-18274885-C-T) – ACMG Classification: Uncertain_significance (0 pts)

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NM_004618.5(TOP3A):c.2923G>A(p.Gly975Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,614,060 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 30)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

TOP3A
NM_004618.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 2.61

Variant links:

Genes affected

TOP3A (HGNC:11992): (DNA topoisomerase III alpha) 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 reducing the number of supercoils and altering the topology of DNA. This enzyme forms a complex with BLM which functions in the regulation of recombination in somatic cells. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Mar 2016]

TOP3A links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 0 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.09257406).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TOP3A	NM_004618.5 link	c.2923G>A	p.Gly975Arg	missense_variant	Exon 19 of 19	ENST00000321105.10	NP_004609.1	Q13472-1
TOP3A	NM_001320759.2 link	c.2638G>A	p.Gly880Arg	missense_variant	Exon 18 of 18		NP_001307688.1	Q13472-3
TOP3A	XM_047436633.1 link	c.2002G>A	p.Gly668Arg	missense_variant	Exon 17 of 17		XP_047292589.1
TOP3A	XM_047436634.1 link	c.2002G>A	p.Gly668Arg	missense_variant	Exon 17 of 17		XP_047292590.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TOP3A	ENST00000321105.10 link	c.2923G>A	p.Gly975Arg	missense_variant	Exon 19 of 19	1	NM_004618.5	ENSP00000321636.5		Q13472-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152170

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000398

AC:

AN:

251490

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135920

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461890

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

727248

show subpopulations

Gnomad4 AFR exome

AF:

0.0000597

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152170

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74340

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000329

Hom.:

Bravo

AF:

0.0000189

ESP6500AA

AF:

0.000227

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Feb 09, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2923G>A (p.G975R) alteration is located in exon 19 (coding exon 19) of the TOP3A gene. This alteration results from a G to A substitution at nucleotide position 2923, causing the glycine (G) at amino acid position 975 to be replaced by an arginine (R). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.11

BayesDel_addAF

Benign

-0.32

BayesDel_noAF

Benign

-0.52

CADD

Benign

DANN

Benign

0.69

DEOGEN2

Benign

0.10

T;T;.

Eigen

Benign

-0.56

Eigen_PC

Benign

-0.53

FATHMM_MKL

Benign

0.43

M_CAP

Benign

0.024

MetaRNN

Benign

0.093

T;T;T

MetaSVM

Benign

-0.78

MutationAssessor

Benign

2.0

M;M;.

PrimateAI

Benign

0.42

PROVEAN

Benign

-1.6

.;N;.

REVEL

Benign

0.074

Sift

Benign

0.12

.;T;.

Sift4G

Uncertain

0.052

T;T;.

Polyphen

0.0010

B;B;.

Vest4

0.072

MutPred

0.21

Gain of methylation at G975 (P = 0.0163);Gain of methylation at G975 (P = 0.0163);.;

MVP

0.15

MPC

0.22

ClinPred

0.13

GERP RS

4.5

Varity_R

0.047

gMVP

0.29

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over