15-89318961-T-TCGG

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1PM2PM4_SupportingPP5

The NM_002693.3(POLG):c.3240_3242dupCCG(p.Arg1081dup) variant causes a disruptive inframe insertion change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

POLG
NM_002693.3 disruptive_inframe_insertion

Scores

Not classified

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5U:1

Conservation

PhyloP100: 7.39

Publications

1 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 6 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 15 uncertain in NM_002693.3

PM2

Very rare variant in population databases, with high coverage;

PM4

Nonframeshift variant in NON repetitive region in NM_002693.3. Strenght limited to Supporting due to length of the change: 1aa.

PP5

Variant 15-89318961-T-TCGG is Pathogenic according to our data. Variant chr15-89318961-T-TCGG is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 419974.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLG	NM_002693.3 link	c.3240_3242dupCCG	p.Arg1081dup	disruptive_inframe_insertion	Exon 20 of 23	ENST00000268124.11	NP_002684.1
POLG	NM_001126131.2 link	c.3240_3242dupCCG	p.Arg1081dup	disruptive_inframe_insertion	Exon 20 of 23		NP_001119603.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POLG	ENST00000268124.11 link	c.3240_3242dupCCG	p.Arg1081dup	disruptive_inframe_insertion	Exon 20 of 23	1	NM_002693.3	ENSP00000268124.5

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251068

AF XY:

0.00

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:

0.00000882

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461888

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727244

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:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000270

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

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

Cov.:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Progressive sclerosing poliodystrophy

Pathogenic:2Uncertain:1

Oct 01, 2018

Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The NM_002693.2:c.3240_3242dup (NP_002684.1:p.Arg1081_Ala1082insArg) [GRCH38: NC_000015.10:g.89318963_89318965dup] variant in POLG gene is interpretated to be a Likely Pathogenic based on ACMG guidelines (PMID: 25741868). This variant meets the following evidence codes reported in the ACMG-guideline. PM2:This variant is absent in key population databases. PM3:Detected in trans with a pathogenic variant for Mitochondrial DNA depletion syndrome 4A (Alpers type) which is a recessive disorder. PP1:This variant is co-segregated with Mitochondrial DNA depletion syndrome 4A (Alpers type) in multiple affected family members. PP2:This is a missense variant in POLG with a low rate of benign and high rate of pathogenic missense variations. PP4:Patient's phenotype or family history is highly specific for POLG. Based on the evidence criteria codes applied, the variant is suggested to be Likely Pathogenic. -

Sep 27, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant, c.3240_3242dup, results in the insertion of 1 amino acid(s) of the POLG protein (p.Arg1081dup), but otherwise preserves the integrity of the reading frame. This variant is present in population databases (no rsID available, gnomAD 0.0009%). This variant has been observed in individual(s) with clinical features of POLG-related conditions (PMID: 20434700, 21880868). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 419974). 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. -

Jul 17, 2022

Baylor Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Pathogenic:2

Jan 28, 2022

GeneDx

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In-frame insertion of 1 amino acids in a non-repeat region; This variant is associated with the following publications: (PMID: 21880868, 20434700) -

Apr 06, 2021

Revvity Omics, Revvity

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Inborn genetic diseases

Pathogenic:1

Feb 15, 2019

Ambry Genetics

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

7.4

Mutation Taster

=58/42

disease causing (ClinVar)

(source)

Splicing

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over