Genetic Variant NM_002693.3:c.2740A>C (chr15-89321007-T-G) – ACMG Classification: Pathogenic (18 pts)

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PS3PM1PM5PP3_ModeratePP5_Very_Strong

The NM_002693.3(POLG):c.2740A>C(p.Thr914Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000187 in 1,614,050 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 Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000329630: Published functional studies demonstrate a damaging effect (Roos et al., 2013)" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T914A) has been classified as Likely pathogenic. The gene POLG is included in the ClinGen Criteria Specification Registry.

Frequency

Genomes: 𝑓 0.000072 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00020 ( 0 hom. )

Consequence

POLG
NM_002693.3 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:16O:1

Conservation

PhyloP100: 7.67

Publications

37 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: G2P, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Orphanet, Ambry Genetics
sensory ataxic neuropathy, dysarthria, and ophthalmoparesis
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, G2P, Ambry Genetics
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

new If you want to explore the variant's impact on the transcript NM_002693.3, check out the Mutation Effect Viewer. This is especially useful for frameshift variants or if you want to visualize the effect of exon loss / intron retention.

ACMG classification

Specifications for POLG are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript

Our verdict: Pathogenic. The variant received 18 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000329630: Published functional studies demonstrate a damaging effect (Roos et al., 2013); SCV002770699: A study shows this variant impairs DNA binding affinity and DNA polymerase activity compared to wild-type (PMID: 23446635).; SCV000754789: Experimental studies have shown that this missense change affects POLG function (PMID: 18828154, 23446635).; SCV000886910: "Well established functional studies show a deleterious effect on POLG."; SCV004750311: An in vitro experimental study suggests this variant affects polymerase gamma mtDNA binding and synthesis (Figure 2, Roos et al. 2013. PubMed ID: 23446635).

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 13 uncertain in NM_002693.3

PM5

Other missense variant is known to change same aminoacid residue: Variant chr15-89321007-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2736250.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.924

PP5

Variant 15-89321007-T-G is Pathogenic according to our data. Variant chr15-89321007-T-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 279961.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_002693.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POLG	NM_002693.3	MANE Select	c.2740A>C	p.Thr914Pro	missense	Exon 18 of 23	NP_002684.1	P54098
	POLG	NM_001126131.2		c.2740A>C	p.Thr914Pro	missense	Exon 18 of 23	NP_001119603.1	P54098

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
POLG	ENST00000268124.11	TSL:1 MANE Select	c.2740A>C	p.Thr914Pro	missense	Exon 18 of 23	ENSP00000268124.5	P54098
POLG	ENST00000442287.6	TSL:1	c.2740A>C	p.Thr914Pro	missense	Exon 18 of 23	ENSP00000399851.2	P54098
POLG	ENST00000636937.2	TSL:5	c.2740A>C	p.Thr914Pro	missense	Exon 18 of 23	ENSP00000516154.1	P54098

Frequencies

GnomAD3 genomes

AF:

0.0000723

AC:

AN:

152236

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000112

AC:

AN:

250820

AF XY:

0.000103

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000247

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000199

AC:

291

AN:

1461814

Hom.:

Cov.:

AF XY:

0.000190

AC XY:

138

AN XY:

727208

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

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:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53346

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.000256

AC:

285

AN:

1112010

Other (OTH)

AF:

0.0000993

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.484

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

100

<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:

0.0000723

AC:

AN:

152236

Hom.:

Cov.:

AF XY:

0.0000807

AC XY:

AN XY:

74370

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41470

American (AMR)

AF:

0.00

AC:

AN:

15290

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10618

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000147

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.484

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:

0.000126

Hom.:

Bravo

AF:

0.000110

ClinVar

ClinVar submissions

Significance:Pathogenic/Likely pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

not provided (7)

Progressive sclerosing poliodystrophy (3)

POLG-related disorder (2)

Mitochondrial DNA depletion syndrome 4b (1)

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 (1)

Progressive sclerosing poliodystrophy;C3150914:Mitochondrial DNA depletion syndrome 4b (1)

Tip-toe gait (1)

Progressive sclerosing poliodystrophy;C1834846:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1;C1843851:Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis;C1843852:Spinocerebellar ataxia with epilepsy;C3713421:Childhood myocerebrohepatopathy spectrum;C4225153:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1 (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.86

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.58

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.97

Eigen

Pathogenic

0.80

Eigen_PC

Pathogenic

0.71

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.86

M_CAP

Pathogenic

0.52

MetaRNN

Pathogenic

0.92

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.5

PhyloP100

7.7

PrimateAI

Uncertain

0.71

PROVEAN

Pathogenic

-5.8

REVEL

Pathogenic

0.98

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0030

PromoterAI

0.010

Neutral

(source)

Varity_R

0.96

gMVP

0.91

Mutation Taster

=0/100

disease causing (ClinVar)

(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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over