rs1288928564

Variant names:

• chr17-18277783-TC-T
• rs1288928564
• NM_004618.5:c.2718delG

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PVS1 PM2 PP5

The NM_004618.5(TOP3A):​c.2718delG​(p.Thr907LeufsTer101) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (no stars). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: TOP3A NM_004618.5 frameshift
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: -0.125
• Publications: 1 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: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 5

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

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 17-18277783-TC-T is Pathogenic according to our data. Variant chr17-18277783-TC-T is described in ClinVar as Pathogenic. ClinVar VariationId is 560202.Status of the report is no_assertion_criteria_provided, 0 stars.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TOP3A	NM_004618.5	MANE Select	c.2718delG	p.Thr907LeufsTer101	frameshift	Exon 18 of 19	NP_004609.1
	TOP3A	NM_001320759.2		c.2433delG	p.Thr812LeufsTer101	frameshift	Exon 17 of 18	NP_001307688.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TOP3A	ENST00000321105.10	TSL:1 MANE Select	c.2718delG	p.Thr907LeufsTer101	frameshift	Exon 18 of 19	ENSP00000321636.5
	TOP3A	ENST00000580095.5	TSL:1	c.2643delG	p.Thr882LeufsTer95	frameshift	Exon 18 of 19	ENSP00000462790.1
	TOP3A	ENST00000469739.6	TSL:2	n.2073delG		non_coding_transcript_exon	Exon 12 of 13

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251386 AF XY: 0.00

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: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: no assertion criteria provided

Pathogenic	VUS	Benign	Condition
1	-	-	Microcephaly, growth restriction, and increased sister chromatid exchange 2 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		-0.13
Mutation Taster		=3/197	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.080		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: rs1288928564; hg19: chr17-18181097;