NM_004618.5:c.2903G>C

Variant names:

• chr17-18274905-C-G
• rs754772043
• NM_004618.5:c.2903G>C

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_004618.5(TOP3A):​c.2903G>C​(p.Arg968Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,886 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R968Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TOP3A NM_004618.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.28
• Publications: 0 publications found

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: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.11429396).

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.2903G>C	p.Arg968Pro	missense	Exon 19 of 19	NP_004609.1	Q13472-1
	TOP3A	NM_001320759.2		c.2618G>C	p.Arg873Pro	missense	Exon 18 of 18	NP_001307688.1	Q13472-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TOP3A	ENST00000321105.10	TSL:1 MANE Select	c.2903G>C	p.Arg968Pro	missense	Exon 19 of 19	ENSP00000321636.5	Q13472-1
	TOP3A	ENST00000580095.5	TSL:1	c.2828G>C	p.Arg943Pro	missense	Exon 19 of 19	ENSP00000462790.1	Q13472-2
	TOP3A	ENST00000924978.1		c.3059G>C	p.Arg1020Pro	missense	Exon 20 of 20	ENSP00000595037.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461886 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727240

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000252 AC: 1 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112010

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 31

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	1	-	Inborn genetic diseases (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.41
CADD	Benign	15
DANN	Benign	0.51
DEOGEN2	Benign	0.073	T
Eigen	Benign	-0.50
Eigen_PC	Benign	-0.53
FATHMM_MKL	Benign	0.30	N
M_CAP	Benign	0.015	T
MetaRNN	Benign	0.11	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Uncertain	2.4	M
PhyloP100		1.3
PrimateAI	Benign	0.38	T
PROVEAN	Benign	-0.84	N
REVEL	Benign	0.12
Sift	Benign	0.17	T
Sift4G	Benign	0.26	T
Polyphen		0.68	P
Vest4		0.27
MutPred		0.25		Loss of MoRF binding (P = 0.0052)
MVP		0.16
MPC		0.42
ClinPred		0.19	T
GERP RS		4.7
PromoterAI		-0.023	Neutral
Varity_R		0.16
gMVP		0.42

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

Other links and lift over

dbSNP: rs754772043; hg19: chr17-18178219;