chr7-144453610-C-T

Position:

• chr7-144453610-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_022445.4(TPK1):​c.667G>A​(p.Gly223Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000397 in 1,613,706 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G223W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000040 (0 hom.)
• Consequence: TPK1 NM_022445.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.79

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 Uncertain_significance. Variant got 3 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, 5 uncertain in NM_022445.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.38613653).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPK1	NM_022445.4	c.667G>A	p.Gly223Arg	missense_variant	9/9	ENST00000360057.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPK1	ENST00000360057.7	c.667G>A	p.Gly223Arg	missense_variant	9/9	1	NM_022445.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152090 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000208

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000756 AC: 19 AN: 251396 Hom.: 0 AF XY: 0.000125 AC XY: 17 AN XY: 135868

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000145

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000218

Gnomad SAS exome AF: 0.000261

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000404 AC: 59 AN: 1461616 Hom.: 0 Cov.: 30 AF XY: 0.0000509 AC XY: 37 AN XY: 727122

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000112

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000227

Gnomad4 SAS exome AF: 0.000267

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000198

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152090 Hom.: 0 Cov.: 32 AF XY: 0.0000404 AC XY: 3 AN XY: 74294

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000208

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000378

ExAC AF: 0.0000576 AC: 7

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.00

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

Labcorp Genetics (formerly Invitae), Labcorp

Oct 24, 2022

This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 223 of the TPK1 protein (p.Gly223Arg). This variant is present in population databases (rs568804217, gnomAD 0.03%). 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: 1000048). 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. Experimental studies have shown that this missense change affects TPK1 function (PMID: 26975778). 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	0.23
BayesDel_addAF	Uncertain	0.10	D
BayesDel_noAF	Pathogenic	0.21
CADD	Uncertain	25
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.53	D;D;.
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Uncertain	0.80	D
M_CAP	Benign	0.066	D
MetaRNN	Benign	0.39	T;T;T
MetaSVM	Uncertain	0.15	D
MutationAssessor	Pathogenic	2.9	M;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.55	T
PROVEAN	Uncertain	-3.5	D;D;D
REVEL	Uncertain	0.56
Sift	Benign	0.030	D;D;T
Sift4G	Uncertain	0.042	D;D;T
Polyphen		1.0	D;D;D
Vest4		0.27
MutPred		0.65		Gain of catalytic residue at G223 (P = 0.0916);.;.;
MVP		0.91
MPC		0.20
ClinPred		0.42	T
GERP RS		5.8
Varity_R		0.46
gMVP		0.56

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: rs568804217; hg19: chr7-144150703;