rs387906936

Variant names:

• chr7-144682975-A-G
• rs387906936
• NM_022445.4:c.119T>C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP5

The NM_022445.4(TPK1):​c.119T>C​(p.Leu40Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,036 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TPK1 NM_022445.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 2.33

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 5 pathogenic changes around while only 0 benign (100%) in NM_022445.4
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-144682975-A-G is Pathogenic according to our data. Variant chr7-144682975-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 30570.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TPK1	NM_022445.4	c.119T>C	p.Leu40Pro	missense_variant	Exon 4 of 9	ENST00000360057.7	NP_071890.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TPK1	ENST00000360057.7	c.119T>C	p.Leu40Pro	missense_variant	Exon 4 of 9	1	NM_022445.4	ENSP00000353165.3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000801 AC: 2 AN: 249690 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135092

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: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460036 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 726448

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Childhood encephalopathy due to thiamine pyrophosphokinase deficiency Pathogenic:2

Dec 02, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 40 of the TPK1 protein (p.Leu40Pro). This variant is present in population databases (rs387906936, gnomAD 0.002%). This missense change has been observed in individuals with clinical features of thiamine metabolism dysfunction syndrome (PMID: 22152682, 28431625). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 30570). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt TPK1 protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change affects TPK1 function (PMID: 26975778, 30483896). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Dec 09, 2011

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Inborn genetic diseases Uncertain:1

Sep 22, 2016

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.43
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.21
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	T;.;T
Eigen	Uncertain	0.26
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.86	D
M_CAP	Benign	0.040	D
MetaRNN	Uncertain	0.74	D;D;D
MetaSVM	Benign	-0.37	T
MutationAssessor	Benign	1.1	L;.;.
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-2.7	D;N;D
REVEL	Uncertain	0.56
Sift	Benign	0.28	T;T;T
Sift4G	Benign	0.27	T;T;.
Polyphen		0.88	P;P;.
Vest4		0.90
MutPred		0.60		Loss of stability (P = 0.0098);Loss of stability (P = 0.0098);Loss of stability (P = 0.0098);
MVP		0.65
MPC		0.69
ClinPred		0.94	D
GERP RS		6.0
Varity_R		0.85
gMVP		0.78

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: rs387906936; hg19: chr7-144380068;