NM_002693.3:c.2218A>G

Variant names:

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_002693.3(POLG):c.2218A>G(p.Asn740Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000044 in 1,614,002 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. N740N) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000043 ( 0 hom. )

Consequence

POLG
NM_002693.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:10

Conservation

PhyloP100: 2.20

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -2 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.2566579).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLG	NM_002693.3 link	c.2218A>G	p.Asn740Asp	missense_variant	Exon 13 of 23	ENST00000268124.11	NP_002684.1	P54098E5KNU5
POLG	NM_001126131.2 link	c.2218A>G	p.Asn740Asp	missense_variant	Exon 13 of 23		NP_001119603.1	P54098E5KNU5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POLG	ENST00000268124.11 link	c.2218A>G	p.Asn740Asp	missense_variant	Exon 13 of 23	1	NM_002693.3	ENSP00000268124.5		P54098

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152092

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000725

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:

0.0000735

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000199

AC:

AN:

251386

Hom.:

AF XY:

0.0000294

AC XY:

AN XY:

135882

show subpopulations

Gnomad AFR exome

AF:

0.000123

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000544

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000431

AC:

AN:

1461792

Hom.:

Cov.:

AF XY:

0.0000426

AC XY:

AN XY:

727216

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000504

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000531

Gnomad4 OTH exome

AF:

0.0000331

GnomAD4 genome

AF:

0.0000526

AC:

AN:

152210

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74418

show subpopulations

Gnomad4 AFR

AF:

0.0000723

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:

0.0000735

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000546

Hom.:

Bravo

AF:

0.0000416

ExAC

AF:

0.0000247

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:5

Jan 10, 2018

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jan 29, 2024

Mayo Clinic Laboratories, Mayo Clinic

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 25, 2013

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

p.Asn740Asp (AAC>GAC): c.2218 A>G in exon 13 of the POLG gene (NM_002693.2). The Asn740Asp missense change in the POLG gene has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. This variant is a non-conservative amino acid substitution of an uncharged Asparagine residue with a negatively charged Aspartic acid residue. While this variant alters a position that is not highly conserved across species and Asparagine is observed at this position in other species, several other missense mutations associated with POLG-related disorders are reported in this region of the protein (N736S, G737R, G746S, W748S). In silico analysis is inconsistent with regard to the effect this variant may have on the protein structure/function. Therefore, based on the currently available information, it is unclear whether Asn740Asp is a disease-causing mutation or a rare benign variant. The variant is found in INFANT-EPI panel(s). -

Jun 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

POLG: PM2 -

Nov 02, 2023

Revvity Omics, Revvity

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

Dec 13, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2218A>G (p.N740D) alteration is located in exon 13 (coding exon 12) of the POLG gene. This alteration results from an A to G substitution at nucleotide position 2218, causing the asparagine (N) at amino acid position 740 to be replaced by an aspartic acid (D). Based on data from gnomAD, the G allele has an overall frequency of 0.002% (6/282780) total alleles studied. The highest observed frequency was 0.008% (2/24964) of African alleles. This amino acid position is well conserved in available vertebrate species. This alteration is predicted to be tolerated by in silico analysis. Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Vascular dementia

Uncertain:1

Oct 01, 2021

Myllykangas group, University of Helsinki

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: research

- -

Progressive sclerosing poliodystrophy

Uncertain:1

Jan 30, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with aspartic acid, which is acidic and polar, at codon 740 of the POLG protein (p.Asn740Asp). This variant is present in population databases (rs78347903, gnomAD 0.005%). This missense change has been observed in individual(s) with vascular dementia (PMID: 35307828). ClinVar contains an entry for this variant (Variation ID: 206519). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt POLG protein function with a negative predictive value of 95%. 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. -

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

Uncertain:1

Jun 16, 2023

New York Genome Center

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.091

BayesDel_addAF

Benign

-0.11

BayesDel_noAF

Benign

-0.22

CADD

Benign

DANN

Benign

0.97

DEOGEN2

Benign

0.35

T;T

Eigen

Benign

-0.33

Eigen_PC

Benign

-0.29

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.81

.;T

M_CAP

Uncertain

0.11

MetaRNN

Benign

0.26

T;T

MetaSVM

Uncertain

0.11

MutationAssessor

Benign

1.6

L;L

PrimateAI

Uncertain

0.51

PROVEAN

Benign

-1.5

N;N

REVEL

Uncertain

0.40

Sift

Benign

0.43

T;T

Sift4G

Benign

0.71

T;T

Polyphen

0.68

P;P

Vest4

0.34

MVP

0.85

MPC

0.53

ClinPred

0.20

GERP RS

0.27

Varity_R

0.21

gMVP

0.62

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

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