rs145843073
Variant summary
Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM1BP4_Strong
The NM_002693.3(POLG):c.1402A>G(p.Asn468Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00081 in 1,614,230 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N468S) has been classified as Uncertain significance.
Frequency
Consequence
NM_002693.3 missense
Scores
Clinical Significance
Conservation
Publications
- progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
- mitochondrial DNA depletion syndrome 4aInheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Orphanet, G2P
- sensory ataxic neuropathy, dysarthria, and ophthalmoparesisInheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, G2P
- autosomal dominant progressive external ophthalmoplegiaInheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
- autosomal recessive progressive external ophthalmoplegiaInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- mitochondrial neurogastrointestinal encephalomyopathyInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- recessive mitochondrial ataxia syndromeInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- spinocerebellar ataxia with epilepsyInheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
- Leigh syndromeInheritance: AR Classification: LIMITED Submitted by: ClinGen
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ACMG classification
Our verdict: Likely_benign. The variant received -2 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.000624 AC: 95AN: 152226Hom.: 0 Cov.: 33 show subpopulations
GnomAD2 exomes AF: 0.000473 AC: 119AN: 251488 AF XY: 0.000456 show subpopulations
GnomAD4 exome AF: 0.000829 AC: 1212AN: 1461886Hom.: 1 Cov.: 34 AF XY: 0.000792 AC XY: 576AN XY: 727244 show subpopulations
Age Distribution
GnomAD4 genome AF: 0.000624 AC: 95AN: 152344Hom.: 0 Cov.: 33 AF XY: 0.000738 AC XY: 55AN XY: 74500 show subpopulations
Age Distribution
ClinVar
Submissions by phenotype
not provided Pathogenic:3Uncertain:6
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PM3 -
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Available data are insufficient to determine the clinical significance of the variant at this time. The frequency of this variant in the general population is uninformative in assessment of its pathogenicity. (http://gnomad.broadinstitute.org) This variant has been identified in at least one individual with clinical features associated with this gene. In multiple individuals, this variant has been seen where an alternate explanation for disease was also identified, suggesting this variant is unlikely to cause disease. Polyphen and MutationTaster yielded discordant predictions regarding whether this amino acid change is damaging to the protein. -
Identified in three members of a family with CPEO, peripheral neuropathy, parkinsonism, and multiple mtDNA deletions in muscle who were also heterozygous for another POLG variant on the other allele; the authors could not conclusively determine whether p.(N468D) was related to the phenotype as siblings carrying p.(N468D) were unaffected (PMID: 15351195, 15181170); Identified as homozygous in an infant with Aicardi-Goutires syndrome who was also homozygous for a pathogenic variant in TREX1 (PMID: 33683010); In silico analysis indicates that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 24122062, 19578034, 24508722, 28284481, 31669236, 32391929, 32347949, 29029963, 29712893, 16401742, 24259288, 21880868, 34426522, 22647225, 23811324, 19752458, 15181170, 32234506, 33513296, 23921535, 35114397, 36291626, 33683010, 35641312, 15351195, 24331360, 25193669, 37138020, 30255931, 31658717, 29997391, 30373890, 23426270) -
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POLG: PM2:Supporting, BP4 -
Progressive sclerosing poliodystrophy Pathogenic:2Benign:1
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The NM_002693.2:c.1402A>G (NP_002684.1:p.Asn468Asp) [GRCH38: NC_000015.10:g.89327198T>C] variant in POLG gene is interpretated to be a Pathogenic based on ACMG guidelines (PMID: 25741868). This variant has been reported in PMID:15351195 ; 16401742 . This variant meets the following evidence codes reported in the ACMG-guideline. PS4:Prevalence of variant in affecteds statistically increased over controls. PS1:This variation causes same amino-acid change as an established pathogenic variant. PS3:Well established functional studies show a deleterious effect on POLG. Based on the evidence criteria codes applied, the variant is suggested to be Pathogenic. -
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Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1 Pathogenic:1Uncertain:1
This variant was determined to be likely pathogenic according to ACMG Guidelines, 2015 [PMID:25741868]. -
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Progressive sclerosing poliodystrophy;C1834846:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1;C1843851:Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis;C3150914:Mitochondrial DNA depletion syndrome 4b;C4225153:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1;C4551995:Mitochondrial DNA depletion syndrome 1 Uncertain:2
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POLG-related disorder Pathogenic:1
The POLG c.1402A>G variant is predicted to result in the amino acid substitution p.Asn468Asp. This variant has been reported in individuals with autosomal recessive POLG-related mitochondrial disease (Palin et al. 2013. PubMed ID: 23811324; Luoma et al. 2004. PubMed ID: 15351195; Woodbridge et al. 2013. PubMed ID: 22647225; González-Vioque et al. 2006. PubMed ID: 16401742; Buzkova et al. 2018. PubMed ID: 30373890). Some POLG variants have also been implicated in autosomal dominant progressive external ophthalmoplegia (PEO), and several PEO patients have been reported to carry this variant in the heterozygous state (Schulte et al. 2009. PubMed ID: 19752458). However, in a second family, heterozygous carriers of the c.1402A>G (p.Asn468Asp) variant were reportedly asymptomatic (Luoma et al. 2004. PubMed ID: 15351195). In ClinVar, this variant has conflicting interpretations of uncertain, likely pathogenic, and pathogenic (https://www.ncbi.nlm.nih.gov/clinvar/variation/206596/). This variant is reported in 0.072% of alleles in individuals of European (Finnish) descent in gnomAD. This variant is interpreted as likely pathogenic for autosomal recessive disease. -
Progressive sclerosing poliodystrophy;C1834846:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1;C1843851:Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis;C3150914:Mitochondrial DNA depletion syndrome 4b;C4225153:Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1 Pathogenic:1
POLG NM_002693.2 exon 16 p.Gly848Ser (c.2542G>A): This variant has been reported in the literature in the compound heterozygous or homozygous state in several individuals with autosomal recessive progressive external opthalmoplegia as well as a wide variety of additional POLG-related phenotypes (Lamantea 2002 PMID:12210792, Weiss 2010 PMID:20513108, Milone 2011 PMID:21670405, Tang 2011 PMID:21880868, Scalais 2012 PMID:22342071, Uusimaa 2013 PMID:23448099, Simon 2014 PMID:2014 PMID:24272679). Literature suggests that this variant is one of the most common pathgenic variants in the POLG gene (Hakonen, 2007 PMID:17426723, Tang 2011 PMID:21880868). This variant is present in 0.03% (40/129136) of European alleles in the Genome Aggregation Database (https://gnomad.broadinstitute.org/variant/15-89865023-C-T). Please note, disease causing variants may be present in control databases at low frequencies, reflective of the general population, carrier status, and/or variable expressivity. This variant is present in ClinVar, with several labs classifying this variant as pathogenic (Variation ID:13502). Evolutionary conservation and computational predictive tools suggest that this variant may impact the protein. In addition, functional studies indicate that this variant leads to decreased enzyme activity and reduced DNA binding affinity (Kasivishwanathan 2009 PMID:19478085). However, these studies may not accurately represent in vivo biological function. In summary, this variant is classified as pathogenic based on the data above. -
Progressive sclerosing poliodystrophy;C3150914:Mitochondrial DNA depletion syndrome 4b Pathogenic:1
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POLG-Related Spectrum Disorders Uncertain:1
This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 1 Uncertain:1
The POLG c.1402A>G; p.Asn468Asp variant is reported in the literature in individuals affected with autosomal recessive progressive external ophthalmoplegia (Luoma 2004, Palin 2013, Woodbridge 2013). The affected individuals identified in these reports were compound heterozygous for the p.Asn468Asp variant while heterozygous carriers in the same family were unaffected. The variant has also been shown to co-segregate with disease in families with autosomal recessive progressive external ophthalmoplegia (Wanrooij 2004). This variant is reported with conflicting interpretations in ClinVar (Variation ID: 206596). Another variant in this region, p.Ala467Thr, is considered the most common pathogenic POLG variant (Variation ID: 13496). However, due to limited functional evidence, the clinical significance of the p.Asn468Asp variant is uncertain. -
Inborn genetic diseases Uncertain:1
The c.1402A>G (p.N468D) alteration is located in exon 7 (coding exon 6) of the POLG gene. This alteration results from a A to G substitution at nucleotide position 1402, causing the asparagine (N) at amino acid position 468 to be replaced by an aspartic acid (D). The altered amino acid is not conserved throughout evolution:_x000D_ _x000D_ The p.N468 amino acid is not conserved in available vertebrate species. The alteration is predicted benign by in silico models:_x000D_ _x000D_ The p.N468D alteration is predicted to be benign by Polyphen and tolerated by SIFT in silico analyses. Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -
Lennox-Gastaut syndrome Uncertain:1
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Hereditary spastic paraplegia Uncertain:1
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not specified Uncertain:1
Variant summary: POLG c.1402A>G (p.Asn468Asp) results in a conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 0.00047 in 251488 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in POLG causing POLG-Related Spectrum Disorders, allowing no conclusion about variant significance. c.1402A>G has been reported in the literature in individuals affected with variety of POLG-related phenotypes. The variant has been reported in three affected family members (and no unaffected family members) with progressive external ophthalmoplegia and parkinsonism as well as a patient with early onset Parkinson's disease, all with a second variant of unknown significance (Luoma_2004, Ylonen_2017). Additionally, the variant was reported along with a pathogenic variant in cases of progressive external ophthalmoplegia and tetraparesis and mitochondrial neurogastrointestinal encephalopathy (Gonzalez-Vioque_2006, Woodbridge_2013). The variant has also been reported in the homozygous state in a patient with congenital ataxia who had no features suggestive of a POLG-related phenotype, therefore ITPR1 variants were considered resposible for congenital ataxia in this patient (Valence_2019). These data indicate that the variant may be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 31658717, 16401742, 15351195, 15181170, 22647225, 29029963, 29997391). ClinVar contains an entry for this variant (Variation ID: 206596). Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -
Mitochondrial disease Uncertain:1
Based on the classification scheme VCGS_Germline_v1.1.1, this variant is classified as 3A-VUS. Following criteria are met: 0102 - Loss-of-function is a known mechanism of disease for this gene. (N) 0108 - This gene is known to be associated with both recessive and dominant disease. Variants in the centre of motif B in the polymerase domain (highly conserved active site), result in dominant disease (PMID: 28480171). (N) 0200 - Variant is predicted to result in a missense amino acid change from an asparagine to an aspartate (exon 7). (N) 0251 - Variant is heterozygous. (N) 0304 - Variant is present in gnomAD <0.01 for a recessive condition (138 heterozygotes, 0 homozygotes). (P) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (6 heterozygotes, 0 homozygotes). (N) 0504 - Same amino acid change has been observed in mammals. (B) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (N) 0705 - No comparable variants have previous evidence for pathogenicity. (N) 0808 - Previous reports of pathogenicity are conflicting. It has been reported as compound heterozygous with another variant in patients with progressive external ophthalmoplegia. However, it has been classified as both pathogenic and VUS in ClinVar (PMID: 22647225, 16401742). (N) 1208 - Inheritance information for this variant is not currently available. (N) Legend: (P) - Pathogenic, (N) - Neutral, (B) - Benign -
Progressive sclerosing poliodystrophy;C1843851:Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis;C3150914:Mitochondrial DNA depletion syndrome 4b Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at