rs143631183

Positions:

• chr15-89330138-C-A

Variant summary

Our verdict is Likely benign. Variant got -4 ACMG points: 0P and 4B. BP4_Moderate BP6 BP7

The NM_002693.3(POLG):​c.798G>T​(p.Val266=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000351 in 1,613,934 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. V266V) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00051 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00033 (1 hom.)
• Consequence: POLG NM_002693.3 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:8
• Conservation: PhyloP100: 0.585

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]

POLGARF (HGNC:):

ACMG classification

Verdict is Likely_benign. Variant got -4 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.35).
• BP6: Variant 15-89330138-C-A is Benign according to our data. Variant chr15-89330138-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 138769.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=5, Uncertain_significance=2, Benign=1}. Variant chr15-89330138-C-A is described in Lovd as [Likely_benign].
• BP7: Synonymous conserved (PhyloP=0.585 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POLG	NM_002693.3	c.798G>T	p.Val266=	synonymous_variant	3/23	ENST00000268124.11
POLGARF	NM_001406557.1	c.*70G>T		3_prime_UTR_variant	3/23
POLG	NM_001126131.2	c.798G>T	p.Val266=	synonymous_variant	3/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLG	ENST00000268124.11	c.798G>T	p.Val266=	synonymous_variant	3/23	1	NM_002693.3	P1

Frequencies

GnomAD3 genomes AF: 0.000512 AC: 78 AN: 152228 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000627

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00157

Gnomad ASJ AF: 0.000864

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000294

Gnomad OTH AF: 0.00239

GnomAD3 exomes AF: 0.000370 AC: 93 AN: 251284 Hom.: 0 AF XY: 0.000309 AC XY: 42 AN XY: 135878

Gnomad AFR exome AF: 0.000739

Gnomad AMR exome AF: 0.000809

Gnomad ASJ exome AF: 0.000298

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000653

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.000387

Gnomad OTH exome AF: 0.000652

GnomAD4 exome AF: 0.000335 AC: 489 AN: 1461706 Hom.: 1 Cov.: 32 AF XY: 0.000330 AC XY: 240 AN XY: 727170

Gnomad4 AFR exome AF: 0.000597

Gnomad4 AMR exome AF: 0.000939

Gnomad4 ASJ exome AF: 0.000383

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000696

Gnomad4 FIN exome AF: 0.0000188

Gnomad4 NFE exome AF: 0.000315

Gnomad4 OTH exome AF: 0.000861

GnomAD4 genome AF: 0.000512 AC: 78 AN: 152228 Hom.: 0 Cov.: 33 AF XY: 0.000511 AC XY: 38 AN XY: 74384

Gnomad4 AFR AF: 0.000627

Gnomad4 AMR AF: 0.00157

Gnomad4 ASJ AF: 0.000864

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000294

Gnomad4 OTH AF: 0.00239

Alfa AF: 0.000437 Hom.: 0

Bravo AF: 0.000672

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.000327

EpiControl AF: 0.000415

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:8

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:1 Benign:4

Likely benign, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -
Likely benign, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Aug 09, 2018	- -
Likely benign, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Feb 01, 2024	POLG: BP4, BP7 -
Likely benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Nov 07, 2019	- -

Progressive sclerosing poliodystrophy Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 30, 2024	- -
Likely benign, criteria provided, single submitter	clinical testing	Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine	Oct 01, 2018	The NM_002693.2:c.798G>T (NP_002684.1:p.Val266=) [GRCH38: NC_000015.10:g.89330138C>A] variant in POLG gene is interpretated to be a Likely Benign based on ACMG guidelines (PMID: 25741868). This variant meets the following evidence codes reported in the ACMG-guideline. BS1:The minor allele frequency of this allele is high for Mitochondrial DNA depletion syndrome 4A (Alpers type). BP4:Computational evidence/predictors indicate no impact on the POLG structure, function, or protein-protein interaction. BP7:The variant is silent with non predicted splice impact. Based on the evidence criteria codes applied, the variant is suggested to be Likely Benign. -

POLG-Related Spectrum Disorders Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

not specified Benign:1

Benign, criteria provided, single submitter

clinical testing

GeneDx

Feb 01, 2013

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

Inborn genetic diseases Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 30, 2016

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.35
CADD	Benign	7.0
DANN	Benign	0.72

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs143631183; hg19: chr15-89873369;