chr15-89328699-G-C

Position:

• chr15-89328699-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM5 PP3

The NM_002693.3(POLG):​c.1156C>G​(p.Arg386Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. R386C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: POLG NM_002693.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.05

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 Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-89328699-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 206589.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=3, Pathogenic=1, Uncertain_significance=6}.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POLG	NM_002693.3	c.1156C>G	p.Arg386Gly	missense_variant	5/23	ENST00000268124.11
POLGARF	NM_001406557.1	c.*428C>G		3_prime_UTR_variant	5/23
POLG	NM_001126131.2	c.1156C>G	p.Arg386Gly	missense_variant	5/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLG	ENST00000268124.11	c.1156C>G	p.Arg386Gly	missense_variant	5/23	1	NM_002693.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive sclerosing poliodystrophy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 22, 2022

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). This variant has not been reported in the literature in individuals affected with POLG-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 386 of the POLG protein (p.Arg386Gly). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.56
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.43
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;D
Eigen	Uncertain	0.64
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.91	.;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.89	D;D
MetaSVM	Pathogenic	0.88	D
MutationAssessor	Pathogenic	3.1	M;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.52	T
PROVEAN	Pathogenic	-5.2	D;D
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0020	D;D
Sift4G	Uncertain	0.011	D;D
Polyphen		1.0	D;D
Vest4		0.91
MutPred		0.50		Gain of ubiquitination at K383 (P = 0.0961);Gain of ubiquitination at K383 (P = 0.0961);
MVP		0.96
MPC		0.75
ClinPred		0.99	D
GERP RS		3.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.8
Varity_R		0.85
gMVP		0.78

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.65		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.65		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs199759055; hg19: chr15-89871930;