rs758454871

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1PP3_Moderate

The NM_002693.3(POLG):c.487C>T(p.Pro163Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000128 in 1,561,606 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P163L) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 34)

Exomes 𝑓: 0.000011 ( 0 hom. )

Consequence

POLG
NM_002693.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:3

Conservation

PhyloP100: 7.57

Publications

3 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 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 was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in NM_002693.3

PP3

MetaRNN computational evidence supports a deleterious effect, 0.86

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLG	NM_002693.3 link	c.487C>T	p.Pro163Ser	missense_variant	Exon 2 of 23	ENST00000268124.11	NP_002684.1	P54098E5KNU5
POLG	NM_001126131.2 link	c.487C>T	p.Pro163Ser	missense_variant	Exon 2 of 23		NP_001119603.1	P54098E5KNU5
POLGARF	NM_001430120.1 link	c.542C>T	p.Ala181Val	missense_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.487C>T	p.Pro163Ser	missense_variant	Exon 2 of 23	1	NM_002693.3	ENSP00000268124.5		P54098
POLGARF	ENST00000706918.1 link	c.542C>T	p.Ala181Val	missense_variant	Exon 1 of 2			ENSP00000516626.1		A0A3B3IS91

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152240

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000327

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000291

AC:

AN:

171530

AF XY:

0.0000425

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000110

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000772

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000106

AC:

AN:

1409366

Hom.:

Cov.:

AF XY:

0.0000129

AC XY:

AN XY:

696018

show subpopulations

African (AFR)

AF:

0.0000313

AC:

AN:

31982

American (AMR)

AF:

0.000129

AC:

AN:

38700

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24610

East Asian (EAS)

AF:

0.0000542

AC:

AN:

36916

South Asian (SAS)

AF:

0.0000123

AC:

AN:

81614

European-Finnish (FIN)

AF:

0.00

AC:

AN:

47512

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5664

European-Non Finnish (NFE)

AF:

0.00000553

AC:

AN:

1084284

Other (OTH)

AF:

0.00

AC:

AN:

58084

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.478

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:

0.0000328

AC:

AN:

152240

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74370

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41466

American (AMR)

AF:

0.000327

AC:

AN:

15294

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68036

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.485

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:

0.0000316

Hom.:

Bravo

AF:

0.0000491

ExAC

AF:

0.0000256

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Jul 27, 2023

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

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: POLG c.487C>T (p.Pro163Ser) results in a non-conservative amino acid change located in the DNA mitochondrial polymerase, exonuclease domain (IPR041336) 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 2.9e-05 in 171530 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.487C>T has been reported in the literature in an individual affected with POLG Related condition (example: Woodbridge_2013). These data do not allow any conclusion about variant significance. One publication reports experimental evidence evaluating an impact on protein function, however, does not allow convincing conclusions about the variant effect (example: Kasahara_2017). The following publications have been ascertained in the context of this evaluation (PMID: 27987238, 22647225). Two submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided

Uncertain:1

Jun 28, 2018

Athena Diagnostics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Progressive sclerosing poliodystrophy

Uncertain:1

Jan 15, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces proline, which is neutral and non-polar, with serine, which is neutral and polar, at codon 163 of the POLG protein (p.Pro163Ser). This variant is present in population databases (rs758454871, gnomAD 0.01%). This missense change has been observed in individual(s) with chronic progressiveexternal ophthalmoplegia, seizure, neuropathy, and ataxia (PMID: 22647225). ClinVar contains an entry for this variant (Variation ID: 586365). 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%. 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.30

BayesDel_addAF

Pathogenic

0.28

BayesDel_noAF

Pathogenic

0.38

CADD

Uncertain

(source)

DANN

Pathogenic

1.0

Eigen

Pathogenic

0.73

Eigen_PC

Uncertain

0.64

FATHMM_MKL

Pathogenic

0.98

M_CAP

Pathogenic

0.46

MetaRNN

Pathogenic

0.86

PhyloP100

7.6

ClinPred

0.99

GERP RS

3.9

PromoterAI

0.00040

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.2

Varity_R

0.86

Mutation Taster

=2/98

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