chr7-144453576-G-T

Position:

• chr7-144453576-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_022445.4(TPK1):​c.701C>A​(p.Pro234Gln) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,578 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P234S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TPK1 NM_022445.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.89

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 5 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
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.794

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TPK1	NM_022445.4	c.701C>A	p.Pro234Gln	missense_variant	9/9	ENST00000360057.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TPK1	ENST00000360057.7	c.701C>A	p.Pro234Gln	missense_variant	9/9	1	NM_022445.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251428 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135884

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: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461578 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 727122

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Oct 05, 2022

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; Has not been previously published as pathogenic or benign to our knowledge -

Childhood encephalopathy due to thiamine pyrophosphokinase deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 11, 2019

This variant is present in population databases (rs749295013, ExAC 0.004%). This sequence change replaces proline with glutamine at codon 234 of the TPK1 protein (p.Pro234Gln). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and glutamine. This variant has not been reported in the literature in individuals with TPK1-related conditions. 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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.33
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.24
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.81	D;D;.
Eigen	Pathogenic	0.72
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.92	D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.79	D;D;D
MetaSVM	Uncertain	0.38	D
MutationAssessor	Pathogenic	2.9	M;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Benign	0.46	T
PROVEAN	Pathogenic	-5.3	D;D;D
REVEL	Pathogenic	0.66
Sift	Benign	0.063	T;D;T
Sift4G	Benign	0.078	T;T;D
Polyphen		1.0	D;D;D
Vest4		0.63
MutPred		0.70		Gain of catalytic residue at P234 (P = 0.0129);.;.;
MVP		0.83
MPC		0.63
ClinPred		0.98	D
GERP RS		5.8
Varity_R		0.69
gMVP		0.86

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: rs749295013; hg19: chr7-144150669;