17-18277723-C-A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PVS1_ModerateBS1_Supporting

The NM_004618.5(TOP3A):c.2779G>T(p.Glu927*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000632 in 1,613,930 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.000052 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000064 ( 0 hom. )

Consequence

TOP3A
NM_004618.5 stop_gained

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 7.51

Publications

0 publications found

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 Gene-Disease associations (from GenCC):

microcephaly, growth restriction, and increased sister chromatid exchange 2
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, PanelApp Australia, Labcorp Genetics (formerly Invitae), G2P
progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5
Inheritance: AR Classification: STRONG, LIMITED Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae)

TOP3A links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0755 CDS is truncated, and there are 0 pathogenic variants in the truncated region.

BS1

Variant frequency is greater than expected in population sas. GnomAd4 allele frequency = 0.0000525 (8/152392) while in subpopulation SAS AF = 0.00165 (8/4834). AF 95% confidence interval is 0.000823. There are 0 homozygotes in GnomAd4. There are 4 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004618.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TOP3A	NM_004618.5	MANE Select	c.2779G>T	p.Glu927*	stop_gained	Exon 18 of 19	NP_004609.1	Q13472-1
	TOP3A	NM_001320759.2		c.2494G>T	p.Glu832*	stop_gained	Exon 17 of 18	NP_001307688.1	Q13472-3

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
TOP3A	ENST00000321105.10	TSL:1 MANE Select	c.2779G>T	p.Glu927*	stop_gained	Exon 18 of 19	ENSP00000321636.5	Q13472-1
TOP3A	ENST00000580095.5	TSL:1	c.2704G>T	p.Glu902*	stop_gained	Exon 18 of 19	ENSP00000462790.1	Q13472-2
TOP3A	ENST00000924978.1		c.2935G>T	p.Glu979*	stop_gained	Exon 19 of 20	ENSP00000595037.1

Frequencies

GnomAD3 genomes

AF:

0.0000525

AC:

AN:

152274

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00165

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000179

AC:

AN:

250912

AF XY:

0.000243

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS 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:

0.0000643

AC:

AN:

1461538

Hom.:

Cov.:

AF XY:

0.0000990

AC XY:

AN XY:

727016

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33468

American (AMR)

AF:

0.00

AC:

AN:

44718

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.00105

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53368

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111764

Other (OTH)

AF:

0.0000497

AC:

AN:

60372

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.494

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000525

AC:

AN:

152392

Hom.:

Cov.:

AF XY:

0.0000537

AC XY:

AN XY:

74524

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41596

American (AMR)

AF:

0.00

AC:

AN:

15306

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00165

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68042

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.438

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.000181

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

ClinVar submissions

Significance:Uncertain significance

Revision:criteria provided, single submitter

View on ClinVar

Pathogenic

VUS

Benign

Condition

Microcephaly, growth restriction, and increased sister chromatid exchange 2 (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.32

BayesDel_noAF

Pathogenic

0.66

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.96

FATHMM_MKL

Pathogenic

1.0

PhyloP100

7.5

Vest4

0.25

GERP RS

5.7

Mutation Taster

=12/188

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.040

Details are displayed if max score is > 0.2

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

Publications

You must be logged in to view publications. This limit was set because tens of millions (!) of queries from AI bots are generated daily.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over