10-100989330-C-T

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2PM5PP3_StrongPP5_Very_Strong

The NM_021830.5(TWNK):c.1120C>T(p.Arg374Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000434 in 1,614,024 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R374Q) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

TWNK
NM_021830.5 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4

Conservation

PhyloP100: 1.90

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 16 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr10-100989331-G-A is described in Lovd as [Pathogenic].

PP3

MetaRNN computational evidence supports a deleterious effect, 0.958

PP5

Variant 10-100989330-C-T is Pathogenic according to our data. Variant chr10-100989330-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 4629.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TWNK	NM_021830.5 link	c.1120C>T	p.Arg374Trp	missense_variant	Exon 1 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.1120C>T	p.Arg374Trp	missense_variant	Exon 1 of 5	1	NM_021830.5	ENSP00000309595.2		Q96RR1-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152176

Hom.:

Cov.:

show subpopulations

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000398

AC:

AN:

251374

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135892

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000342

AC:

AN:

1461848

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

727230

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000360

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152176

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74340

show subpopulations

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000756

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3

Pathogenic:2

Feb 01, 2010

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Sep 27, 2022

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: C10orf2 c.1120C>T (p.Arg374Trp) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 251374 control chromosomes (gnomAD). c.1120C>T has been reported in the literature in individuals affected with Progressive External Ophthalmoplegia, with confirmed segregation in two families (Echaniz-Laguna_2010), and in one individual with a positive family history suggesting autosomal dominant inheritance (Vandenberghe_2021). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One ClinVar submitter has assessed the variant since 2014: the variant was classified as likely pathogenic. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

not provided

Pathogenic:2

Nov 19, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 25133958, 24091712, 20880070, 22353293, 31692161, 19513767, 18971204, 20479361, 34409151, 38703036) -

Jan 07, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 374 of the TWNK protein (p.Arg374Trp). This variant is present in population databases (rs267606682, gnomAD 0.0009%). This missense change has been observed in individuals with clinical features of autosomal dominant progressive external ophthalmoplegia (PMID: 19513767, 25133958, 34409151). ClinVar contains an entry for this variant (Variation ID: 4629). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt TWNK protein function with a positive predictive value of 95%. This variant disrupts the p.Arg374 amino acid residue in TWNK. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11431692, 20880070, 32161153). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.66

BayesDel_addAF

Pathogenic

0.53

BayesDel_noAF

Pathogenic

0.52

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Uncertain

0.51

D;.

Eigen

Pathogenic

0.71

Eigen_PC

Uncertain

0.66

FATHMM_MKL

Uncertain

0.83

LIST_S2

Uncertain

0.96

D;D

M_CAP

Pathogenic

0.54

MetaRNN

Pathogenic

0.96

D;D

MetaSVM

Pathogenic

0.94

MutationAssessor

Pathogenic

3.4

M;M

PROVEAN

Pathogenic

-7.3

D;D

REVEL

Pathogenic

0.76

Sift

Pathogenic

0.0

D;D

Sift4G

Pathogenic

0.0010

D;D

Polyphen

1.0

D;D

Vest4

0.95

MVP

1.0

MPC

0.83

ClinPred

0.99

GERP RS

4.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.79

gMVP

0.94

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over