rs78347903

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM1BP4_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:8

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:

POLGARF (HGNC:):

POLGARF links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 0 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 11 uncertain in NM_002693.3

BP4

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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE
POLG	NM_002693.3 linkuse as main transcript	c.2218A>G	p.Asn740Asp	missense_variant	13/23	ENST00000268124.11
POLGARF	NM_001406557.1 linkuse as main transcript	c.*1490A>G		3_prime_UTR_variant	13/23
POLG	NM_001126131.2 linkuse as main transcript	c.2218A>G	p.Asn740Asp	missense_variant	13/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLG	ENST00000268124.11 linkuse as main transcript	c.2218A>G	p.Asn740Asp	missense_variant	13/23	1	NM_002693.3	P1

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:8

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Nov 25, 2013	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). -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Nov 02, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Athena Diagnostics	Jan 10, 2018	- -

POLG-Related Spectrum Disorders

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 12, 2017

The p.N740D variant (also known as c.2218A>G), located in coding exon 12 of the POLG gene, results from an A to G substitution at nucleotide position 2218. The asparagine at codon 740 is replaced by aspartic acid, an amino acid with highly similar properties. This amino acid position is not well conserved in available vertebrate species, and aspartic acid 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. -

Vascular dementia

Uncertain:1

Uncertain significance, no assertion criteria provided

research

Myllykangas group, University of Helsinki

Oct 01, 2021

- -

Progressive sclerosing poliodystrophy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 11, 2023

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). 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) performed at Invitae 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

Uncertain significance, criteria provided, single submitter

clinical testing

New York Genome Center

Jun 16, 2023

- -

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

M_CAP

Uncertain

0.11

MetaRNN

Benign

0.26

T;T

MetaSVM

Uncertain

0.11

MutationAssessor

Benign

1.6

L;L

MutationTaster

Benign

1.0

D;D

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