rs766501874

Variant names:

• chr15-89333605-C-T
• rs766501874
• NM_001430120.1:c.205G>A

Variant summary

Our verdict is Likely benign. The variant received -6 ACMG points: 4P and 10B. PM1 PM2 BP4_Moderate BP6_Very_Strong

The NM_001430120.1(POLGARF):​c.205G>A​(p.Ala69Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000019 in 1,580,682 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 8/10 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A69G) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000020 (0 hom.)
• Consequence: POLGARF NM_001430120.1 missense
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:5
• Conservation: PhyloP100: -1.45
• Publications: 0 publications found

Genes affected

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]

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: Likely_benign. The variant received -6 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 11 benign, 10 uncertain in NM_001430120.1
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.085697055).
• BP6: Variant 15-89333605-C-T is Benign according to our data. Variant chr15-89333605-C-T is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 378909.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001430120.1. 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
	POLGARF	NM_001430120.1	MANE Select	c.205G>A	p.Ala69Thr	missense	Exon 1 of 2	NP_001417049.1	A0A3B3IS91
	POLG	NM_002693.3	MANE Select	c.150G>A	p.Gln50Gln	synonymous	Exon 2 of 23	NP_002684.1	P54098
	POLG	NM_001126131.2		c.150G>A	p.Gln50Gln	synonymous	Exon 2 of 23	NP_001119603.1	P54098

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	POLGARF	ENST00000706918.1	MANE Select	c.205G>A	p.Ala69Thr	missense	Exon 1 of 2	ENSP00000516626.1	A0A3B3IS91
	POLG	ENST00000268124.11	TSL:1 MANE Select	c.150G>A	p.Gln50Gln	synonymous	Exon 2 of 23	ENSP00000268124.5	P54098
	POLG	ENST00000442287.6	TSL:1	c.150G>A	p.Gln50Gln	synonymous	Exon 2 of 23	ENSP00000399851.2	P54098

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 151022 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.0000296

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000456 AC: 10 AN: 219330 AF XY: 0.0000412

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000606

Gnomad FIN exome AF: 0.0000597

Gnomad NFE exome AF: 0.0000619

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000196 AC: 28 AN: 1429546 Hom.: 0 Cov.: 32 AF XY: 0.0000127 AC XY: 9 AN XY: 710662

⚠️ 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: 32824

American (AMR) AF: 0.00 AC: 0 AN: 43028

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25760

East Asian (EAS) AF: 0.0000257 AC: 1 AN: 38928

South Asian (SAS) AF: 0.0000355 AC: 3 AN: 84502

European-Finnish (FIN) AF: 0.0000215 AC: 1 AN: 46430

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5648

European-Non Finnish (NFE) AF: 0.0000201 AC: 22 AN: 1093300

Other (OTH) AF: 0.0000169 AC: 1 AN: 59126

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0000000000000908162), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 151136 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 73878

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

African (AFR) AF: 0.00 AC: 0 AN: 41214

American (AMR) AF: 0.00 AC: 0 AN: 15184

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3466

East Asian (EAS) AF: 0.00 AC: 0 AN: 5142

South Asian (SAS) AF: 0.00 AC: 0 AN: 4764

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 292

European-Non Finnish (NFE) AF: 0.0000296 AC: 2 AN: 67454

Other (OTH) AF: 0.00 AC: 0 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.0000000000983081), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.0000363 AC: 4

ClinVar

ClinVar submissions

Significance: Benign/Likely benign

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	-	2	not provided (2)
-	-	2	Progressive sclerosing poliodystrophy (2)
-	-	1	Inborn genetic diseases (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.28
BayesDel_noAF	Benign	-0.93
CADD	Benign	5.4
DANN	Benign	0.71
FATHMM_MKL	Benign	0.011	N
MetaRNN	Benign	0.086	T
PhyloP100		-1.4
GERP RS		-0.71
PromoterAI		0.050	Neutral
Mutation Taster		=100/0	polymorphism

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: rs766501874; hg19: chr15-89876836; COSMIC: COSV51524045; COSMIC: COSV51524045;