chr8-143310110-G-C

Position:

• chr8-143310110-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_052963.3(TOP1MT):​c.1661C>G​(p.Thr554Arg) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,248 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 (★). Synonymous variant affecting the same amino acid position (i.e. T554T) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TOP1MT NM_052963.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.63

Genes affected

TOP1MT (HGNC:29787): (DNA topoisomerase I mitochondrial) This gene encodes a mitochondrial DNA topoisomerase that plays a role in the modification of DNA topology. The encoded protein is a type IB topoisomerase and catalyzes the transient breaking and rejoining of DNA to relieve tension and DNA supercoiling generated in the mitochondrial genome during replication and transcription. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, May 2012]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.835

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TOP1MT	NM_052963.3	c.1661C>G	p.Thr554Arg	missense_variant	13/14	ENST00000329245.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TOP1MT	ENST00000329245.9	c.1661C>G	p.Thr554Arg	missense_variant	13/14	1	NM_052963.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461248 Hom.: 0 Cov.: 37 AF XY: 0.00 AC XY: 0 AN XY: 726952

Gnomad4 AFR exome AF: 0.00

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: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000227

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 07, 2022

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on TOP1MT protein function. This variant has not been reported in the literature in individuals affected with TOP1MT-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with arginine, which is basic and polar, at codon 554 of the TOP1MT protein (p.Thr554Arg). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.28
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Benign	22
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.62	D;.;.;.
Eigen	Uncertain	0.66
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.98	D;.;.;D
M_CAP	Benign	0.014	T
MetaRNN	Pathogenic	0.84	D;D;D;D
MetaSVM	Uncertain	0.25	D
MutationAssessor	Pathogenic	3.4	M;.;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Benign	0.46	T
PROVEAN	Pathogenic	-5.3	D;D;D;D
REVEL	Uncertain	0.44
Sift	Uncertain	0.015	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	D;.;.;.
Vest4		0.78
MutPred		0.64		Gain of MoRF binding (P = 0.0163);.;.;.;
MVP		0.76
MPC		0.79
ClinPred		1.0	D
GERP RS		4.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.50
gMVP		0.70

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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

Other links and lift over

dbSNP: rs761519188; hg19: chr8-144392280;