15-89333177-C-T

Variant names:

Variant summary

Our verdict is Uncertain significance. Variant got -4 ACMG points: 0P and 4B. BS2

This summary comes from the ClinGen Evidence Repository: The c.578G>A (p.Arg193Gln) variant in POLG has been reported with an allele frequency in the population at 0.2 % in African Americans in gnomAD. It is also seen in the homozygous state in 1 individual in gnomAD (BS2). This variant is not reported in the literature and no computational data is available. In summary, this variant meets criteria to be classified as uncertain significance for primary mitochondrial disease inherited in a recessive manner. ntDNA Mitochondrial ACMG-AMP Criteria for POLG applied: BS2. LINK:https://erepo.genome.network/evrepo/ui/classification/CA241475/MONDO:0044970/014

Frequency

Genomes: 𝑓 0.00066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000050 ( 0 hom. )

Consequence

POLG
NM_002693.3 missense

Scores

Clinical Significance

Uncertain significance reviewed by expert panel U:8B:4

Conservation

PhyloP100: 0.369

Variant links:

Genes affected

POLG (HGNC:9179): (DNA polymerase gamma, catalytic subunit) Mitochondrial DNA polymerase is heterotrimeric, consisting of a homodimer of accessory subunits plus a catalytic subunit. The protein encoded by this gene is the catalytic subunit of mitochondrial DNA polymerase. The encoded protein contains a polyglutamine tract near its N-terminus that may be polymorphic. Defects in this gene are a cause of progressive external ophthalmoplegia with mitochondrial DNA deletions 1 (PEOA1), sensory ataxic neuropathy dysarthria and ophthalmoparesis (SANDO), Alpers-Huttenlocher syndrome (AHS), and mitochondrial neurogastrointestinal encephalopathy syndrome (MNGIE). Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Jul 2008]

POLG links:

POLGARF (HGNC:56246): (POLG alternative reading frame) This gene uses the same transcript as the POLG gene but has a CUG start codon and an alternate reading frame that makes a 260 aa protein. This protein is distinct from POLG isoforms and may interact with P32 (also known as C1QBP), a mitochondrial matrix protein thought to be involved in the expression of mitochondrial genome-encoded proteins. POLGARF protein may bind P32 and sequester it in the nucleolus. Interestingly, some disease-causing mutations thought to be in POLG may instead be associated with POLGARF. [provided by RefSeq, May 2022]

POLGARF links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got -4 ACMG points.

BS2

For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLG	NM_002693.3 link	c.578G>A	p.Arg193Gln	missense_variant	Exon 2 of 23	ENST00000268124.11	NP_002684.1	P54098E5KNU5
POLG	NM_001126131.2 link	c.578G>A	p.Arg193Gln	missense_variant	Exon 2 of 23		NP_001119603.1	P54098E5KNU5
POLGARF	NM_001430120.1 link	c.633G>A	p.Ala211Ala	synonymous_variant	Exon 1 of 2		NP_001417049.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POLG	ENST00000268124.11 link	c.578G>A	p.Arg193Gln	missense_variant	Exon 2 of 23	1	NM_002693.3	ENSP00000268124.5		P54098
POLGARF	ENST00000706918.1 link	c.633G>A	p.Ala211Ala	synonymous_variant	Exon 1 of 2			ENSP00000516626.1		A0A3B3IS91

Frequencies

GnomAD3 genomes

AF:

0.000663

AC:

101

AN:

152228

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00236

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:

0.0000147

Gnomad OTH

AF:

0.000955

GnomAD3 exomes

AF:

0.000151

AC:

AN:

211358

Hom.:

AF XY:

0.0000954

AC XY:

AN XY:

115318

show subpopulations

Gnomad AFR exome

AF:

0.00183

Gnomad AMR exome

AF:

0.000139

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:

0.000195

GnomAD4 exome

AF:

0.0000503

AC:

AN:

1412880

Hom.:

Cov.:

AF XY:

0.0000345

AC XY:

AN XY:

696658

show subpopulations

Gnomad4 AFR exome

AF:

0.00182

Gnomad4 AMR exome

AF:

0.000104

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:

0.00000184

Gnomad4 OTH exome

AF:

0.000120

GnomAD4 genome

AF:

0.000663

AC:

101

AN:

152346

Hom.:

Cov.:

AF XY:

0.000497

AC XY:

AN XY:

74498

show subpopulations

Gnomad4 AFR

AF:

0.00236

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:

0.0000147

Gnomad4 OTH

AF:

0.000945

Alfa

AF:

0.0000860

Hom.:

Bravo

AF:

0.000699

ESP6500AA

AF:

0.00159

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.000207

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:8Benign:4

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

not provided

Uncertain:4Benign:1

May 21, 2021

Mayo Clinic Laboratories, Mayo Clinic

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 21, 2023

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Available data are insufficient to determine the clinical significance of the variant at this time. The frequency of this variant in the general population is uninformative in assessment of its pathogenicity. (http://gnomad.broadinstitute.org) Assessment of experimental analysis yielded inconclusive results regarding the impact of this variant on protein function. The effect of variant in mtDNA mutability was shown to be neutral in a yeast model (PMID 25462018). However, this has not been studied in a mammalian model system. -

May 18, 2021

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is associated with the following publications: (PMID: 25462018) -

Nov 06, 2017

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Progressive sclerosing poliodystrophy

Benign:2

Oct 01, 2018

Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The NM_002693.2:c.578G>A (NP_002684.1:p.Arg193Gln) [GRCH38: NC_000015.10:g.89333177C>T] variant in POLG gene is interpretated to be a Likely Benign based on ACMG guidelines (PMID: 25741868). This variant meets the following evidence codes reported in the ACMG-guideline. BS1:The minor allele frequency of this allele is high for Mitochondrial DNA depletion syndrome 4A (Alpers type). BP4:Computational evidence/predictors indicate no impact on the POLG structure, function, or protein-protein interaction. Based on the evidence criteria codes applied, the variant is suggested to be Likely Benign. -

Jan 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Progressive sclerosing poliodystrophy;C1834846:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1;C1843851:Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis;C3150914:Mitochondrial DNA depletion syndrome 4b;C4225153:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1;C4551995:Mitochondrial DNA depletion syndrome 1

Uncertain:1

Nov 09, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

POLG-Related Spectrum Disorders

Uncertain:1

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Inborn genetic diseases

Uncertain:1

Jan 30, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R193Q variant (also known as c.578G>A), located in coding exon 1 of the POLG gene, results from a G to A substitution at nucleotide position 578. The arginine at codon 193 is replaced by glutamine, an amino acid with highly similar properties. This amino acid position is not well conserved in available vertebrate species, and glutamine is the reference amino acid in other vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Mitochondrial disease

Uncertain:1

May 07, 2021

ClinGen Mitochondrial Disease Nuclear and Mitochondrial Variant Curation Expert Panel, ClinGen

Significance: Uncertain significance

Review Status: reviewed by expert panel

Collection Method: curation

The c.578G>A (p.Arg193Gln) variant in POLG has been reported with an allele frequency in the population at 0.2 % in African Americans in gnomAD. It is also seen in the homozygous state in 1 individual in gnomAD (BS2). This variant is not reported in the literature and no computational data is available. In summary, this variant meets criteria to be classified as uncertain significance for primary mitochondrial disease inherited in a recessive manner. ntDNA Mitochondrial ACMG-AMP Criteria for POLG applied: BS2. -

POLG-related disorder

Benign:1

Aug 11, 2023

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.064

BayesDel_addAF

Benign

-0.39

BayesDel_noAF

Benign

-0.34

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Benign

0.19

T;T

Eigen

Benign

-0.46

Eigen_PC

Benign

-0.31

FATHMM_MKL

Benign

0.72

LIST_S2

Uncertain

0.88

.;D

M_CAP

Benign

0.021

MetaRNN

Benign

0.010

T;T

MetaSVM

Benign

-0.45

MutationAssessor

Benign

1.3

L;L

PrimateAI

Uncertain

0.51

PROVEAN

Benign

0.76

N;N

REVEL

Benign

0.16

Sift

Benign

0.42

T;T

Sift4G

Benign

0.39

T;T

Polyphen

0.019

B;B

Vest4

0.089

MVP

0.76

MPC

0.18

ClinPred

0.014

GERP RS

2.6

Varity_R

0.074

gMVP

0.41

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