7-144453613-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PM5

The NM_022445.4(TPK1):c.664G>A(p.Asp222Asn) variant causes a missense change. The variant allele was found at a frequency of 0.0000242 in 1,613,800 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. D222H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000024 (0 hom.)
• Consequence: TPK1 NM_022445.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.12

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a chain Thiamin pyrophosphokinase 1 (size 242) in uniprot entity TPK1_HUMAN there are 17 pathogenic changes around while only 1 benign (94%) in NM_022445.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-144453613-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 419232.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPK1	NM_022445.4	c.664G>A	p.Asp222Asn	missense_variant	9/9	ENST00000360057.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPK1	ENST00000360057.7	c.664G>A	p.Asp222Asn	missense_variant	9/9	1	NM_022445.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152066 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000725

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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

GnomAD3 exomes AF: 0.0000358 AC: 9 AN: 251392 Hom.: 0 AF XY: 0.0000368 AC XY: 5 AN XY: 135866

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000528

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000239 AC: 35 AN: 1461616 Hom.: 0 Cov.: 30 AF XY: 0.0000234 AC XY: 17 AN XY: 727130

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152184 Hom.: 0 Cov.: 32 AF XY: 0.0000403 AC XY: 3 AN XY: 74382

Gnomad4 AFR AF: 0.0000723

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000862 Hom.: 0

Bravo AF: 0.0000529

ESP6500AA AF: 0.000454 AC: 2

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.0000412 AC: 5

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Childhood encephalopathy due to thiamine pyrophosphokinase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 19, 2024

This sequence change replaces aspartic acid, which is acidic and polar, with asparagine, which is neutral and polar, at codon 222 of the TPK1 protein (p.Asp222Asn). This variant is present in population databases (rs368458768, gnomAD 0.008%). This variant has not been reported in the literature in individuals affected with TPK1-related conditions. ClinVar contains an entry for this variant (Variation ID: 657167). 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) performed at Invitae indicates that this missense variant is not expected to disrupt TPK1 protein function with a negative predictive value of 80%. 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	0.13
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Benign	-0.29
Cadd	Uncertain	25
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.52	D;D;.
Eigen	Uncertain	0.37
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Uncertain	0.85	D
M_CAP	Uncertain	0.21	D
MetaRNN	Uncertain	0.67	D;D;D
MetaSVM	Uncertain	-0.10	T
MutationAssessor	Pathogenic	3.1	M;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.58	T
PROVEAN	Uncertain	-3.7	D;D;D
REVEL	Uncertain	0.38
Sift	Uncertain	0.0070	D;D;D
Sift4G	Benign	0.13	T;T;T
Polyphen		1.0	D;D;D
Vest4		0.54
MVP		0.86
MPC		0.58
ClinPred		0.91	D
GERP RS		4.6
Varity_R		0.81
gMVP		0.69

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

Other links and lift over

dbSNP: rs368458768; hg19: chr7-144150706;