15-89322814-C-G

Variant names:

• chr15-89322814-C-G
• rs149058889
• NM_002693.3:c.2354G>C

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_002693.3(POLG):​c.2354G>C​(p.Gly785Ala) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,776 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G785D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: POLG NM_002693.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 3.07
• Publications: 0 publications found

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]

POLG Gene-Disease associations (from GenCC):

• progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• mitochondrial DNA depletion syndrome 4a

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Ambry Genetics
• sensory ataxic neuropathy, dysarthria, and ophthalmoparesis

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, G2P
• autosomal dominant progressive external ophthalmoplegia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• autosomal recessive progressive external ophthalmoplegia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• mitochondrial neurogastrointestinal encephalomyopathy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• recessive mitochondrial ataxia syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• spinocerebellar ataxia with epilepsy

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Leigh syndrome

  Inheritance: AR Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_002693.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.179849).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_002693.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POLG	NM_002693.3	MANE Select	c.2354G>C	p.Gly785Ala	missense	Exon 14 of 23	NP_002684.1	P54098
	POLG	NM_001126131.2		c.2354G>C	p.Gly785Ala	missense	Exon 14 of 23	NP_001119603.1	P54098

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POLG	ENST00000268124.11	TSL:1 MANE Select	c.2354G>C	p.Gly785Ala	missense	Exon 14 of 23	ENSP00000268124.5	P54098
	POLG	ENST00000442287.6	TSL:1	c.2354G>C	p.Gly785Ala	missense	Exon 14 of 23	ENSP00000399851.2	P54098
	POLG	ENST00000636937.2	TSL:5	c.2354G>C	p.Gly785Ala	missense	Exon 14 of 23	ENSP00000516154.1	P54098

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461776 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727198

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53384

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5738

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111974

Other (OTH) AF: 0.00 AC: 0 AN: 60392

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.093
BayesDel_addAF	Uncertain	0.080	D
BayesDel_noAF	Benign	-0.12
CADD	Benign	21
DANN	Benign	0.85
DEOGEN2	Uncertain	0.52	D
Eigen	Benign	-0.19
Eigen_PC	Benign	-0.025
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Benign	0.71	T
M_CAP	Benign	0.067	D
MetaRNN	Benign	0.18	T
MetaSVM	Uncertain	0.33	D
MutationAssessor	Benign	0.90	L
PhyloP100		3.1
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	-0.70	N
REVEL	Uncertain	0.30
Sift	Benign	0.64	T
Sift4G	Benign	0.80	T
Polyphen		0.026	B
Vest4		0.14
MutPred		0.45		Gain of glycosylation at P783 (P = 0.1319)
MVP		0.89
MPC		0.30
ClinPred		0.62	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.9
Varity_R		0.22
gMVP		0.67

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

Other links and lift over

dbSNP: rs149058889; hg19: chr15-89866045;