Genetic Variant NM_021830.5:c.952G>A (chr10-100989162-G-A) – ACMG Classification: Likely_pathogenic (7 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1PM2PP2PP5_Moderate

The NM_021830.5(TWNK):c.952G>A(p.Ala318Thr) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,612,496 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. A318A) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

TWNK
NM_021830.5 missense

Scores

Clinical Significance

Pathogenic criteria provided, single submitter P:2O:1

Conservation

PhyloP100: 5.79

Publications

14 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: Likely_pathogenic. The variant received 7 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_021830.5

PM2

Very rare variant in population databases, with high coverage;

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 10-100989162-G-A is Pathogenic according to our data. Variant chr10-100989162-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 4630.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_021830.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TWNK	NM_021830.5	MANE Select	c.952G>A	p.Ala318Thr	missense	Exon 1 of 5	NP_068602.2
TWNK	NM_001163812.2		c.952G>A	p.Ala318Thr	missense	Exon 1 of 5	NP_001157284.1
TWNK	NR_160738.1		n.1620G>A		non_coding_transcript_exon	Exon 1 of 5

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
TWNK	ENST00000311916.8	TSL:1 MANE Select	c.952G>A	p.Ala318Thr	missense	Exon 1 of 5	ENSP00000309595.2
TWNK	ENST00000370228.2	TSL:1	c.952G>A	p.Ala318Thr	missense	Exon 1 of 5	ENSP00000359248.1
TWNK	ENST00000643860.1		n.952G>A		non_coding_transcript_exon	Exon 1 of 5	ENSP00000494389.1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152134

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:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251330

AF XY:

0.00

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 FIN exome

AF:

0.0000462

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1460362

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726180

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33428

American (AMR)

AF:

0.00

AC:

AN:

44690

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26110

East Asian (EAS)

AF:

0.00

AC:

AN:

39668

South Asian (SAS)

AF:

0.00

AC:

AN:

86248

European-Finnish (FIN)

AF:

0.0000187

AC:

AN:

53398

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1110724

Other (OTH)

AF:

0.00

AC:

AN:

60330

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

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:

0.00000657

AC:

AN:

152134

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74306

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41428

American (AMR)

AF:

0.0000654

AC:

AN:

15282

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10602

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2078

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

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

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2Other:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Infantile onset spinocerebellar ataxia

Pathogenic:1Other:1

Nov 01, 2007

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

GeneReviews

Significance:not provided

Review Status:no classification provided

Collection Method:literature only

See cases

Pathogenic:1

Aug 14, 2020

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

ACMG classification criteria: PS4, PM2, PM3, PP2, PP3

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.17

BayesDel_addAF

Pathogenic

0.32

BayesDel_noAF

Pathogenic

0.23

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.40

Eigen

Uncertain

0.68

Eigen_PC

Pathogenic

0.70

FATHMM_MKL

Uncertain

0.96

LIST_S2

Uncertain

0.89

M_CAP

Uncertain

0.26

MetaRNN

Uncertain

0.70

MetaSVM

Uncertain

0.64

MutationAssessor

Pathogenic

3.1

PhyloP100

5.8

PROVEAN

Uncertain

-2.6

REVEL

Pathogenic

0.76

Sift

Uncertain

0.0060

Sift4G

Uncertain

0.010

Polyphen

0.99

Vest4

0.48

MutPred

0.84

Gain of helix (P = 0.062)

MVP

0.96

MPC

1.3

ClinPred

0.93

GERP RS

5.9

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.40

gMVP

0.86

Mutation Taster

=9/91

disease causing (ClinVar)

(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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over