NM_002693.3(POLG):c.2636A>G (p.Gln879Arg) AND Progressive sclerosing poliodystrophy

Germline classification:: Conflicting interpretations of pathogenicity (2 submissions)
Last evaluated:: Dec 12, 2023
Review status:: criteria provided, conflicting classifications

Somatic classification of clinical impact:: None
Review status:: (0/4) 0 stars out of maximum of 4 stars
no assertion criteria provided

Somatic classification of oncogenicity:: None
Review status:: (0/4) 0 stars out of maximum of 4 stars
no assertion criteria provided

Record status:: current
Accession:: RCV000758312.8

Allele description [Variation Report for NM_002693.3(POLG):c.2636A>G (p.Gln879Arg)]

NM_002693.3(POLG):c.2636A>G (p.Gln879Arg)

Genes:

POLG:DNA polymerase gamma, catalytic subunit [Gene - OMIM - HGNC]
POLGARF:POLG alternative reading frame [Gene - HGNC]

Variant type:

single nucleotide variant

Cytogenetic location:

15q26.1

Genomic location:

Preferred name:

NM_002693.3(POLG):c.2636A>G (p.Gln879Arg)

Other names:

p.Q879R:CAG>CGG

HGVS:

NC_000015.10:g.89321223T>C
NG_008218.2:g.18573A>G
NM_001126131.2:c.2636A>G
NM_002693.3:c.2636A>GMANE SELECT
NP_001119603.1:p.Gln879Arg
NP_002684.1:p.Gln879Arg
NP_002684.1:p.Gln879Arg
LRG_765t1:c.2636A>G
LRG_765:g.18573A>G
LRG_765p1:p.Gln879Arg
NC_000015.9:g.89864454T>C
NM_002693.2:c.2636A>G

Protein change:

Q879R

Links:

dbSNP: rs368587966

NCBI 1000 Genomes Browser:

rs368587966

Molecular consequence:

NM_001126131.2:c.2636A>G - missense variant - [Sequence Ontology: SO:0001583]
NM_002693.3:c.2636A>G - missense variant - [Sequence Ontology: SO:0001583]

Condition(s)

Name:: Progressive sclerosing poliodystrophy (MTDPS4A)
Synonyms:: Alpers disease; Alpers diffuse degeneration of cerebral gray matter with hepatic cirrhosis; Alpers progressive infantile poliodystrophy; See all synonyms [MedGen]
Identifiers:: MONDO: MONDO:0008758; MedGen: C0205710; Orphanet: 726; OMIM: 203700

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Submission Accession	Submitter	Review Status (Assertion method)	Clinical Significance (Last evaluated)	Origin	Method	Citations
SCV000886970	Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine	criteria provided, single submitter (ACMG Guidelines, 2015)	Pathogenic (Oct 1, 2018)	germline	clinical testing	PubMed (1) [See all records that cite this PMID]
SCV001386878	Invitae	criteria provided, single submitter (Invitae Variant Classification Sherloc (09022015))	Uncertain significance (Dec 12, 2023)	germline	clinical testing	PubMed (1) [See all records that cite this PMID]

Submission Accession

Submitter

Review Status
(Assertion method)

Clinical Significance
(Last evaluated)

Origin

Method

Citations

SCV000886970

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

criteria provided, single submitter

(ACMG Guidelines, 2015)

Pathogenic
(Oct 1, 2018)

germline

clinical testing

PubMed (1)
[See all records that cite this PMID]

SCV001386878

Invitae

criteria provided, single submitter

(Invitae Variant Classification Sherloc (09022015))

Uncertain significance
(Dec 12, 2023)

germline

clinical testing

PubMed (1)
[See all records that cite this PMID]

Help

Summary from all submissions

Ethnicity	Origin	Affected	Individuals	Families	Chromosomes tested	Number Tested	Family history	Method
not provided	germline	unknown	not provided	not provided	not provided	not provided	not provided	clinical testing

Citations

PubMed

Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology.

Richards S, Aziz N, Bale S, Bick D, Das S, Gastier-Foster J, Grody WW, Hegde M, Lyon E, Spector E, Voelkerding K, Rehm HL; ACMG Laboratory Quality Assurance Committee..

Genet Med. 2015 May;17(5):405-24. doi: 10.1038/gim.2015.30. Epub 2015 Mar 5.

PubMed [citation]

PMID:: 25741868
PMCID:: PMC4544753

Sherloc: a comprehensive refinement of the ACMG-AMP variant classification criteria.

Nykamp K, Anderson M, Powers M, Garcia J, Herrera B, Ho YY, Kobayashi Y, Patil N, Thusberg J, Westbrook M; Invitae Clinical Genomics Group., Topper S.

Genet Med. 2017 Oct;19(10):1105-1117. doi: 10.1038/gim.2017.37. Epub 2017 May 11. Erratum in: Genet Med. 2020 Jan;22(1):240-242.

PubMed [citation]

PMID:: 28492532
PMCID:: PMC5632818

Details of each submission

From Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine, SCV000886970.1

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	clinical testing	PubMed (1)

Description

The NM_002693.2:c.2636A>G (NP_002684.1:p.Gln879Arg) [GRCH38: NC_000015.10:g.89321223T>C] variant in POLG gene is interpretated to be a Pathogenic based on ACMG guidelines (PMID: 25741868). This variant meets the following evidence codes reported in the ACMG-guideline. PS1:This variation causes same amino-acid change as an established pathogenic variant. PM1:This variant is in mutational hot spot or a well-studied functional domain without benign variation. PM2:This variant is absent in key population databases. 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 Pathogenic.

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

From Invitae, SCV001386878.5

#	Ethnicity	Individuals	Chromosomes Tested	Family History	Method	Citations
1	not provided	not provided	not provided	not provided	clinical testing	PubMed (1)

Description

This sequence change replaces glutamine, which is neutral and polar, with arginine, which is basic and polar, at codon 879 of the POLG protein (p.Gln879Arg). This variant is present in population databases (rs368587966, gnomAD 0.02%). This variant has not been reported in the literature in individuals affected with POLG-related conditions. ClinVar contains an entry for this variant (Variation ID: 206532). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on POLG protein function. 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.

#	Sample				Method		Observation
#	Origin	Affected	Number tested	Tissue	Purpose	Method	Individuals	Allele frequency	Families	Co-occurrences
1	germline	unknown	not provided	not provided	not provided		not provided	not provided	not provided	not provided

Last Updated: Feb 20, 2024

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