rs121918053

Variant names:

Your query was ambiguous. Multiple possible variants found:

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1PM5PP3_StrongPP5

The NM_002693.3(POLG):c.2557C>T(p.Arg853Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,998 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R853Q) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

POLG
NM_002693.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6U:1

Conservation

PhyloP100: 1.67

Publications

26 publications found

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 Gene-Disease associations (from GenCC):

progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
mitochondrial DNA depletion syndrome 4a
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Orphanet, G2P
sensory ataxic neuropathy, dysarthria, and ophthalmoparesis
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, G2P
autosomal dominant progressive external ophthalmoplegia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
autosomal recessive progressive external ophthalmoplegia
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
mitochondrial neurogastrointestinal encephalomyopathy
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
recessive mitochondrial ataxia syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
spinocerebellar ataxia with epilepsy
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
Leigh syndrome
Inheritance: AR Classification: LIMITED Submitted by: ClinGen

POLG links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

PM1

In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_002693.3

PM5

Other missense variant is known to change same aminoacid residue: Variant chr15-89321776-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 206529.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.995

PP5

Variant 15-89321777-G-A is Pathogenic according to our data. Variant chr15-89321777-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 13512.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLG	NM_002693.3 link	c.2557C>T	p.Arg853Trp	missense_variant	Exon 16 of 23	ENST00000268124.11	NP_002684.1	P54098E5KNU5
POLG	NM_001126131.2 link	c.2557C>T	p.Arg853Trp	missense_variant	Exon 16 of 23		NP_001119603.1	P54098E5KNU5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POLG	ENST00000268124.11 link	c.2557C>T	p.Arg853Trp	missense_variant	Exon 16 of 23	1	NM_002693.3	ENSP00000268124.5		P54098

Frequencies

GnomAD3 genomes

AF:

0.0000329

AC:

AN:

152182

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

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:

0.0000441

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000119

AC:

AN:

251374

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS 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:

0.0000137

AC:

AN:

1461816

Hom.:

Cov.:

AF XY:

0.00000963

AC XY:

AN XY:

727212

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.0000224

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.0000162

AC:

AN:

1111972

Other (OTH)

AF:

0.0000166

AC:

AN:

60388

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.465

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000329

AC:

AN:

152182

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74336

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41446

American (AMR)

AF:

0.0000654

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10620

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000441

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.535

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.000107

Hom.:

Bravo

AF:

0.0000189

ExAC

AF:

0.0000247

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Progressive sclerosing poliodystrophy

Pathogenic:2

Feb 28, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dec 10, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 853 of the POLG protein (p.Arg853Trp). This variant is present in population databases (rs121918053, gnomAD 0.003%). This missense change has been observed in individual(s) with early-onset Parkinson disease and/or progressive external ophthalmoplegia and ptosis (PMID: 16401742, 16634032, 27185166). ClinVar contains an entry for this variant (Variation ID: 13512). 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 expected to disrupt POLG protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects POLG function (PMID: 20185557). This variant disrupts the p.Arg853 amino acid residue in POLG. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 18546365, 19478085, 20185557). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1

Pathogenic:1

May 01, 2006

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

- -

Mitochondrial DNA depletion syndrome

Pathogenic:1

Aug 09, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: POLG c.2557C>T (p.Arg853Trp) results in a non-conservative amino acid change located in the DNA polymerase gamma, palm domain (IPR047580) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.2e-05 in 251374 control chromosomes. c.2557C>T has been reported in the literature as biallelic genotypes in individuals affected with features of autosomal recessive POLG Related-Mitochondrial DNA Depletion Syndrome (example, Davidson_2006, Gonzalez-Vioque_2006, Qualo_2020). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function, however, does not allow convincing conclusions about the variant effect (Stumpf_2010). The following publications have been ascertained in the context of this evaluation (PMID: 16634032, 16401742, 33258288, 20185557). Two submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. One submitter classified the variant as likely pathogenic and one submitter classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

not provided

Pathogenic:1

Aug 01, 2023

CeGaT Center for Human Genetics Tuebingen

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

POLG: PM2, PM3, PM5, PP3, PS3:Supporting -

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

Pathogenic:1

Apr 02, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Uncertain:1

Jun 05, 2020

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant classified as Uncertain Significance - Favor Pathogenic. The p.Arg853Trp variant in POLG has been reported in the compound heterozygous state in an individual affected with progressive external ophthalmoplegia and ptosis 2, and in 2 individuals with early-onset Parkinson's disease and features of mitochondrial disease (segregating with disease in 1 affected family member; Davidzon 2006 PMID: 16634032, Rempe 2016 PMID: 27185166, Gonzalez-Vioque 2006 PMID: 16401742). This variant has also been reported in ClinVar (Variation ID: 13512) and was identified in 4/129112 of European chromosomes by gnomAD (http://gnomad.broadinstitute.org). In vitro functional studies provide some evidence that this variant impacts protein function (Stumpf 2010 PMID: 20185557). In summary, while there is some suspicion for a pathogenic role, the clinical significance of this variant is uncertain. ACMG/AMP Criteria applied: PM2, PP1, PP3, PM3_Supporting, PS3_Supporting. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.96

BayesDel_addAF

Pathogenic

0.48

BayesDel_noAF

Pathogenic

0.53

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.98

D;D

Eigen

Uncertain

0.53

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.95

LIST_S2

Pathogenic

1.0

.;D

M_CAP

Pathogenic

0.80

MetaRNN

Pathogenic

1.0

D;D

MetaSVM

Pathogenic

0.81

MutationAssessor

Pathogenic

3.5

H;H

PhyloP100

1.7

PrimateAI

Pathogenic

0.80

PROVEAN

Pathogenic

-7.8

D;D

REVEL

Pathogenic

0.88

Sift

Pathogenic

0.0

D;D

Sift4G

Pathogenic

0.0

D;D

Polyphen

1.0

D;D

Vest4

0.98

MutPred

0.99

Loss of catalytic residue at R853 (P = 0.0058);Loss of catalytic residue at R853 (P = 0.0058);

MVP

0.99

MPC

0.67

ClinPred

1.0

GERP RS

2.1

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.2

Varity_R

0.95

gMVP

0.98

Mutation Taster

=10/90

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over