rs886051522

Positions:

• chr15-89318925-A-T

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_Strong BP6

The NM_002693.3(POLG):​c.3273+6T>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,804 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: POLG NM_002693.3 splice_region, intron
• Scores: Splicing: ADA: 0.01080
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2 B:1
• Conservation: PhyloP100: 0.393

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 -5 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).
• BP6: Variant 15-89318925-A-T is Benign according to our data. Variant chr15-89318925-A-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 317324.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
POLG	NM_002693.3	c.3273+6T>A		splice_region_variant, intron_variant		ENST00000268124.11	NP_002684.1
POLG	NM_001126131.2	c.3273+6T>A		splice_region_variant, intron_variant			NP_001119603.1
POLGARF	NM_001406557.1	c.*2545+6T>A		splice_region_variant, intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
POLG	ENST00000268124.11	c.3273+6T>A		splice_region_variant, intron_variant		1	NM_002693.3	ENSP00000268124.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000797 AC: 2 AN: 250908 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135688

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461804 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727210

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: 0.0000108

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000468 Hom.: 0

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Progressive sclerosing poliodystrophy Uncertain:1 Benign:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 08, 2023	This sequence change falls in intron 20 of the POLG gene. It does not directly change the encoded amino acid sequence of the POLG protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (no rsID available, gnomAD 0.002%). 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: 317324). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. 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. -
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.3273+6T>A (NP_002684.1:p.=) [GRCH38: NC_000015.10:g.89318925A>T] 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. BP4:Computational evidence/predictors indicate no impact on the POLG structure, function, or protein-protein interaction. BP6:Reputable source(s) without shared data suggest the variant is benign. 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 12, 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	8.4
DANN	Benign	0.85

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.011
dbscSNV1_RF	Benign	0.23
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: rs886051522; hg19: chr15-89862156;