chr10-100990470-G-A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PP2PP5BP4

The NM_021830.5(TWNK):c.1519G>A(p.Val507Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000124 in 1,614,120 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000012 ( 0 hom. )

Consequence

TWNK
NM_021830.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts P:1U:3O:1

Conservation

PhyloP100: 2.96

Publications

13 publications found

Variant links:

Genes affected

TWNK (HGNC:1160): (twinkle mtDNA helicase) This gene encodes a hexameric DNA helicase which unwinds short stretches of double-stranded DNA in the 5' to 3' direction and, along with mitochondrial single-stranded DNA binding protein and mtDNA polymerase gamma, is thought to play a key role in mtDNA replication. The protein localizes to the mitochondrial matrix and mitochondrial nucleoids. Mutations in this gene cause infantile onset spinocerebellar ataxia (IOSCA) and progressive external ophthalmoplegia (PEO) and are also associated with several mitochondrial depletion syndromes. Alternative splicing results in multiple transcript variants encoding distinct isoforms.[provided by RefSeq, Aug 2009]

TWNK Gene-Disease associations (from GenCC):

progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
mitochondrial DNA depletion syndrome 7 (hepatocerebral type)
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae)
autosomal dominant progressive external ophthalmoplegia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
mitochondrial DNA depletion syndrome, hepatocerebrorenal form
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
Perrault syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

TWNK links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 36 curated pathogenic missense variants (we use a threshold of 10). The gene has 6 curated benign missense variants. Gene score misZ: 1.6071 (below the threshold of 3.09). Trascript score misZ: 2.58 (below the threshold of 3.09). GenCC associations: The gene is linked to progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3, mitochondrial DNA depletion syndrome 7 (hepatocerebral type), Perrault syndrome, autosomal dominant progressive external ophthalmoplegia, mitochondrial DNA depletion syndrome, hepatocerebrorenal form.

PP5

Variant 10-100990470-G-A is Pathogenic according to our data. Variant chr10-100990470-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 162051.

BP4

Computational evidence support a benign effect (MetaRNN=0.25000972). . Strength limited to SUPPORTING due to the PP5.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TWNK	NM_021830.5 link	c.1519G>A	p.Val507Ile	missense_variant	Exon 3 of 5	ENST00000311916.8	NP_068602.2	Q96RR1-1E5KSY5Q9H6V3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TWNK	ENST00000311916.8 link	c.1519G>A	p.Val507Ile	missense_variant	Exon 3 of 5	1	NM_021830.5	ENSP00000309595.2		Q96RR1-1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152216

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000199

AC:

AN:

251486

AF XY:

0.0000221

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000116

AC:

AN:

1461786

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

727210

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.0000447

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53406

Middle Eastern (MID)

AF:

0.000347

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000989

AC:

AN:

1111938

Other (OTH)

AF:

0.0000166

AC:

AN:

60390

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.437

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152334

Hom.:

Cov.:

AF XY:

0.0000268

AC XY:

AN XY:

74490

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41570

American (AMR)

AF:

0.0000653

AC:

AN:

15308

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.000414

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68038

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.558

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1Uncertain:3Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:2

Aug 29, 2017

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The V507I variant has previously been reported in two siblings with autosomal recessive Perrault syndrome; these siblings were also compound heterozygous for a second missense variant in C10orf2 and neither variant was identified in these individual's unaffected siblings (Morino et al., 2014). The V507I variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The V507I variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. This substitution occurs at a position where amino acids with similar properties to Valine are tolerated across species. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. In summary, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -

Nov 18, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces valine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 507 of the TWNK protein (p.Val507Ile). This variant is present in population databases (rs369588002, gnomAD 0.01%). This missense change has been observed in individuals with Perrault syndrome (PMID: 25355836, 32281099). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 162051). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on TWNK protein function. 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. -

Perrault syndrome 5

Pathogenic:1

Nov 25, 2014

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

- -

not specified

Uncertain:1

Nov 21, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: C10orf2 c.1519G>A (p.Val507Ile) results in a conservative amino acid change located in the DNA helicase, DnaB-like, C-terminal domain (IPR007694) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 2e-05 in 251486 control chromosomes (gnomAD). c.1519G>A has been reported in the literature in individuals affected with Perrault syndrome and the variant co-segregated with the disease (Morino_2014, Gotta_2020). 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: 31455392, 32281099, 32234020, 25355836, 28178980, 27551684, 35035228). Two submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as VUS-possibly pathogenic. -

Perrault syndrome

Other:1

GeneReviews

Significance:not provided

Review Status:no classification provided

Collection Method:literature only

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.091

BayesDel_addAF

Benign

-0.14

BayesDel_noAF

Benign

-0.24

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.37

.;T;.;.

Eigen

Benign

-0.15

Eigen_PC

Benign

-0.018

FATHMM_MKL

Uncertain

0.83

LIST_S2

Benign

0.84

T;T;T;T

M_CAP

Uncertain

0.17

MetaRNN

Benign

0.25

T;T;T;T

MetaSVM

Uncertain

0.016

MutationAssessor

Uncertain

2.1

.;M;M;.

PhyloP100

3.0

PROVEAN

Benign

-0.59

.;N;N;.

REVEL

Pathogenic

0.72

Sift

Benign

0.13

.;T;T;.

Sift4G

Uncertain

0.039

.;D;T;.

Polyphen

0.64, 0.67

.;P;P;.

Vest4

0.70, 0.51

MVP

0.41

MPC

0.59

ClinPred

0.25

GERP RS

4.8

Varity_R

0.045

gMVP

0.33

Mutation Taster

=37/63

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over