rs780479868

Positions:

chr20-3218604-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_033453.4(ITPA):c.383C>T(p.Pro128Leu) variant causes a missense change. The variant allele was found at a frequency of 0.0000304 in 1,613,660 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000030 ( 0 hom. )

Consequence

ITPA
NM_033453.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 4.59

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ITPA	NM_033453.4 linkuse as main transcript	c.383C>T	p.Pro128Leu	missense_variant	6/8	ENST00000380113.8	NP_258412.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ITPA	ENST00000380113.8 linkuse as main transcript	c.383C>T	p.Pro128Leu	missense_variant	6/8	1	NM_033453.4	ENSP00000369456	P1	Q9BY32-1

Frequencies

GnomAD3 genomes

AF:

0.0000328

AC:

AN:

152250

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000965

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:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000160

AC:

AN:

249858

Hom.:

AF XY:

0.00000739

AC XY:

AN XY:

135408

show subpopulations

Gnomad AFR exome

AF:

0.0000621

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:

0.0000267

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000301

AC:

AN:

1461410

Hom.:

Cov.:

AF XY:

0.0000275

AC XY:

AN XY:

727052

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

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:

0.0000351

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000328

AC:

AN:

152250

Hom.:

Cov.:

AF XY:

0.0000403

AC XY:

AN XY:

74382

show subpopulations

Gnomad4 AFR

AF:

0.0000965

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000847

Hom.:

Bravo

AF:

0.0000416

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.00

AC:

EpiCase

AF:

0.000218

EpiControl

AF:

0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inosine triphosphatase deficiency

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 05, 2022

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 128 of the ITPA protein (p.Pro128Leu). This variant is present in population databases (rs780479868, gnomAD 0.008%). This variant has not been reported in the literature in individuals affected with ITPA-related conditions. ClinVar contains an entry for this variant (Variation ID: 423919). 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: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Mar 02, 2017

The P128L variant in the ITPA gene has not been reported previously as a pathogenic variant, nor as a benign variant, to our knowledge. The P128L variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The P128L variant is a semi-conservative amino acid substitution, which may impact secondary protein structure as these residues differ in some properties. This substitution occurs at a position that is conserved across species. In silico analysis predicts this variant is probably damaging to the protein structure/function. We interpret P128L as a variant of uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.16

BayesDel_addAF

Pathogenic

0.30

BayesDel_noAF

Pathogenic

0.37

CADD

Uncertain

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.84

D;.;.

Eigen

Uncertain

0.24

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Benign

0.68

LIST_S2

Benign

0.84

T;T;T

M_CAP

Benign

0.012

MetaRNN

Uncertain

0.73

D;D;D

MetaSVM

Benign

-0.59

MutationAssessor

Pathogenic

3.0

M;.;.

MutationTaster

Benign

1.0

D;D;D

PrimateAI

Uncertain

0.57

PROVEAN

Pathogenic

-5.8

D;D;D

REVEL

Benign

0.27

Sift

Uncertain

0.0010

D;D;D

Sift4G

Uncertain

0.010

D;D;D

Polyphen

0.63

P;.;.

Vest4

0.82

MutPred

0.46

Loss of disorder (P = 0.0244);.;.;

MVP

0.63

MPC

0.67

ClinPred

0.93

GERP RS

5.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.37

gMVP

0.77

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over