rs200086262

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PVS1_StrongPM2PP5_Very_Strong

The NM_033453.4(ITPA):c.452G>A(p.Trp151*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000322 in 1,613,968 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 Pathogenic (★★).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000034 ( 0 hom. )

Consequence

ITPA
NM_033453.4 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:4

Conservation

PhyloP100: 8.05

Publications

8 publications found

Variant links:

Genes affected

ITPA (HGNC:6176): (inosine triphosphatase) This gene encodes an inosine triphosphate pyrophosphohydrolase. The encoded protein hydrolyzes inosine triphosphate and deoxyinosine triphosphate to the monophosphate nucleotide and diphosphate. This protein, which is a member of the HAM1 NTPase protein family, is found in the cytoplasm and acts as a homodimer. Defects in the encoded protein can result in inosine triphosphate pyrophosphorylase deficiency which causes an accumulation of ITP in red blood cells. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jun 2012]

ITPA Gene-Disease associations (from GenCC):

genetic developmental and epileptic encephalopathy
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
developmental and epileptic encephalopathy, 35
Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
inosine triphosphatase deficiency
Inheritance: AR Classification: MODERATE Submitted by: Ambry Genetics

ITPA links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 14 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.227 CDS is truncated, and there are 3 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 20-3221881-G-A is Pathogenic according to our data. Variant chr20-3221881-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 218089.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ITPA	NM_033453.4 link	c.452G>A	p.Trp151*	stop_gained	Exon 7 of 8	ENST00000380113.8	NP_258412.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ITPA	ENST00000380113.8 link	c.452G>A	p.Trp151*	stop_gained	Exon 7 of 8	1	NM_033453.4	ENSP00000369456.3

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152226

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:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.000188

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000557

AC:

AN:

251172

AF XY:

0.0000295

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.000419

Gnomad NFE exome

AF:

0.0000440

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000342

AC:

AN:

1461742

Hom.:

Cov.:

AF XY:

0.0000275

AC XY:

AN XY:

727190

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.000104

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.000394

AC:

AN:

53284

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000180

AC:

AN:

1111998

Other (OTH)

AF:

0.00

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.487

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:

0.0000131

AC:

AN:

152226

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74376

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41450

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.000188

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68044

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000653

Hom.:

Bravo

AF:

0.00000378

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.0000412

AC:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Pathogenic:2

Nov 10, 2017

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The W151X variant has been previously reported in the homozygous state in two siblings with progressive microcephaly, seizures, and developmental delay; ITPase activity in erythrocytes of one of the siblings was found to be severely reduced (Kevelam et. al., 2015). The W151X variant is observed in 11/25636 (0.04%) alleles from individuals of Finnish background, in large population cohorts (Lek et al., 2016). This nonsense variant is predicted to cause loss of normal protein function through protein truncation as the last 44 amino acids are lost. Therefore, we interpret W151X as a pathogenic variant.

Feb 16, 2025

Laboratory of Genetics, Children's Clinical University Hospital Latvia

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Developmental and epileptic encephalopathy, 35

Pathogenic:1

Oct 01, 2015

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

Inosine triphosphatase deficiency

Pathogenic:1

Nov 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change creates a premature translational stop signal (p.Trp151*) in the ITPA gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 44 amino acid(s) of the ITPA protein. This variant is present in population databases (rs200086262, gnomAD 0.04%). This premature translational stop signal has been observed in individuals with ITPA-related conditions (PMID: 26224535, 30856165). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 218089). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant disrupts a region of the ITPA protein in which other variant(s) (p.Arg178Cys) have been observed in individuals with ITPA-related conditions (PMID: 26224535). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.53

BayesDel_noAF

Pathogenic

0.54

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.0

.;.;.

Eigen

Pathogenic

0.96

Eigen_PC

Pathogenic

0.85

FATHMM_MKL

Uncertain

0.94

LIST_S2

Benign

0.0

.;.;.

MetaRNN

Benign

0.0

.;.;.

MutationAssessor

Benign

0.0

.;.;.

PhyloP100

8.0

PROVEAN

Benign

0.0

.;.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.;.

Sift4G

Pathogenic

0.0

.;.;.

Vest4

0.93

GERP RS

5.3

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

2.7

Mutation Taster

=1/199

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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