NM_022445.4:c.677T>A

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM1BP4_Strong

The NM_022445.4(TPK1):c.677T>A(p.Val226Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000062 in 1,613,964 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V226I) has been classified as Uncertain significance.

Frequency

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

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

TPK1
NM_022445.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 2.63

Publications

3 publications found

Variant links:

Genes affected

TPK1 (HGNC:17358): (thiamin pyrophosphokinase 1) The protein encoded by this gene functions as a homodimer and catalyzes the conversion of thiamine to thiamine pyrophosphate, a cofactor for some enzymes of the glycolytic and energy production pathways. Defects in this gene are a cause of thiamine metabolism dysfunction syndrome-5. [provided by RefSeq, Apr 2017]

TPK1 Gene-Disease associations (from GenCC):

childhood encephalopathy due to thiamine pyrophosphokinase deficiency
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
Leigh syndrome
Inheritance: AR Classification: MODERATE Submitted by: ClinGen

TPK1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_022445.4

BP4

Computational evidence support a benign effect (MetaRNN=0.05386299).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TPK1	NM_022445.4 link	c.677T>A	p.Val226Asp	missense_variant	Exon 9 of 9	ENST00000360057.7	NP_071890.2	Q9H3S4-1A0A090N8Y0

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPK1	ENST00000360057.7 link	c.677T>A	p.Val226Asp	missense_variant	Exon 9 of 9	1	NM_022445.4	ENSP00000353165.3		Q9H3S4-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152210

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000192

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:

0.0000278

AC:

AN:

251402

AF XY:

0.0000368

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000381

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000616

AC:

AN:

1461636

Hom.:

Cov.:

AF XY:

0.00000688

AC XY:

AN XY:

727130

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33458

American (AMR)

AF:

0.00

AC:

AN:

44706

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.000227

AC:

AN:

39690

South Asian (SAS)

AF:

0.00

AC:

AN:

86246

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111836

Other (OTH)

AF:

0.00

AC:

AN:

60388

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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:

0.00000656

AC:

AN:

152328

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74486

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41564

American (AMR)

AF:

0.00

AC:

AN:

15296

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.000193

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.0000247

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Feb 05, 2024

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.677T>A (p.V226D) alteration is located in exon 9 (coding exon 8) of the TPK1 gene. This alteration results from a T to A substitution at nucleotide position 677, causing the valine (V) at amino acid position 226 to be replaced by an aspartic acid (D). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Childhood encephalopathy due to thiamine pyrophosphokinase deficiency

Uncertain:1

Sep 07, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces valine with aspartic acid at codon 226 of the TPK1 protein (p.Val226Asp). The valine residue is weakly conserved and there is a large physicochemical difference between valine and aspartic acid. This variant is present in population databases (rs550639617, ExAC 0.03%). This variant has not been reported in the literature in individuals affected with TPK1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.15

BayesDel_addAF

Benign

-0.12

BayesDel_noAF

Benign

-0.10

CADD

Benign

(source)

DANN

Benign

0.85

DEOGEN2

Benign

0.40

T;T;.

Eigen

Benign

-0.42

Eigen_PC

Benign

-0.30

FATHMM_MKL

Benign

0.17

M_CAP

Benign

0.022

MetaRNN

Benign

0.054

T;T;T

MetaSVM

Benign

-0.76

MutationAssessor

Uncertain

2.4

M;.;.

PhyloP100

2.6

PrimateAI

Benign

0.39

PROVEAN

Benign

-1.8

N;N;N

REVEL

Uncertain

0.42

Sift

Benign

0.57

T;T;T

Sift4G

Benign

0.60

T;T;T

Polyphen

0.0010

B;B;B

Vest4

0.44

MutPred

0.53

Gain of disorder (P = 0.0064);.;.;

MVP

0.35

MPC

0.25

ClinPred

0.12

GERP RS

4.6

Varity_R

0.71

gMVP

0.68

Mutation Taster

=72/28

polymorphism

(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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over