15-89318553-T-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_002693.3(POLG):c.3470A>C(p.Asn1157Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 152,078 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. N1157S) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: POLG NM_002693.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.30

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 Pathogenic. Variant got 10 ACMG points.

• PM1: In a helix (size 22) in uniprot entity DPOG1_HUMAN there are 5 pathogenic changes around while only 1 benign (83%) in NM_002693.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-89318553-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 206565.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=2, Uncertain_significance=1}.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.971

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POLG	NM_002693.3	c.3470A>C	p.Asn1157Thr	missense_variant	21/23	ENST00000268124.11
POLGARF	NM_001406557.1	c.*2742A>C		3_prime_UTR_variant	21/23
POLG	NM_001126131.2	c.3470A>C	p.Asn1157Thr	missense_variant	21/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLG	ENST00000268124.11	c.3470A>C	p.Asn1157Thr	missense_variant	21/23	1	NM_002693.3	P1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152078 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000242

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: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1461028 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726838

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152078 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74284

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000151

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Mar 13, 2024

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Sep 16, 2020

Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Progressive sclerosing poliodystrophy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 10, 2022

This sequence change replaces asparagine, which is neutral and polar, with threonine, which is neutral and polar, at codon 1157 of the POLG protein (p.Asn1157Thr). This variant is not present in population databases (gnomAD no frequency). 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: 1209397). 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) performed at Invitae indicates that this missense variant is expected to disrupt 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.90
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.20
Cadd	Pathogenic	27
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.96	D;D
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Pathogenic	0.53	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	H;H
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-5.5	D;D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;D
Vest4		0.83
MutPred		0.85		Gain of catalytic residue at N1157 (P = 0.0769);Gain of catalytic residue at N1157 (P = 0.0769);
MVP		0.99
MPC		0.66
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.92
gMVP		0.84

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

LitVar

Other links and lift over

dbSNP: rs548076633; hg19: chr15-89861784;