15-89333347-G-T

Position:

• chr15-89333347-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_002693.3(POLG):​c.408C>A​(p.Asp136Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,252 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 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 nucleotide change resulting in same amino acid change has been previously reported as Likely benignin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D136Y) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 34)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: POLG NM_002693.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.66

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:56246): (POLG alternative reading frame) This gene uses the same transcript as the POLG gene but has a CUG start codon and an alternate reading frame that makes a 260 aa protein. This protein is distinct from POLG isoforms and may interact with P32 (also known as C1QBP), a mitochondrial matrix protein thought to be involved in the expression of mitochondrial genome-encoded proteins. POLGARF protein may bind P32 and sequester it in the nucleolus. Interestingly, some disease-causing mutations thought to be in POLG may instead be associated with POLGARF. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 13 uncertain in NM_002693.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.19692397).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
POLG	NM_002693.3	c.408C>A	p.Asp136Glu	missense_variant	2/23	ENST00000268124.11
POLGARF	NM_001406557.1	c.463C>A	p.Pro155Thr	missense_variant	2/23
POLG	NM_001126131.2	c.408C>A	p.Asp136Glu	missense_variant	2/23

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
POLG	ENST00000268124.11	c.408C>A	p.Asp136Glu	missense_variant	2/23	1	NM_002693.3	P1
POLGARF	ENST00000706918.1	c.463C>A	p.Pro155Thr	missense_variant	1/2			P1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152252 Hom.: 0 Cov.: 34

Gnomad AFR AF: 0.0000241

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: 1415842 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 701130

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: 0.00000657 AC: 1 AN: 152252 Hom.: 0 Cov.: 34 AF XY: 0.0000134 AC XY: 1 AN XY: 74392

Gnomad4 AFR AF: 0.0000241

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

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.30
BayesDel_addAF	Benign	-0.013	T
BayesDel_noAF	Benign	-0.26
CADD	Uncertain	24
DANN	Benign	0.86
DEOGEN2	Benign	0.25	T;T
Eigen	Benign	-0.29
Eigen_PC	Benign	-0.15
FATHMM_MKL	Uncertain	0.88	D
M_CAP	Uncertain	0.17	D
MetaRNN	Benign	0.20	T;T
MetaSVM	Benign	-0.37	T
MutationAssessor	Benign	1.3	L;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.62	T
PROVEAN	Benign	0.080	N;N
REVEL	Benign	0.22
Sift	Benign	1.0	T;T
Sift4G	Benign	1.0	T;T
Polyphen		0.43	B;B
Vest4		0.35
MutPred		0.42		Gain of disorder (P = 0.2129);Gain of disorder (P = 0.2129);
MVP		0.88
MPC		0.16
ClinPred		0.30	T
GERP RS		3.1
Varity_R		0.20
gMVP		0.51

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: rs115109291; hg19: chr15-89876578;