20-3218618-A-G

Position:

chr20-3218618-A-G

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2BP4_StrongBS1_Supporting

The NM_033453.4(ITPA):c.397A>G(p.Arg133Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000725 in 1,613,022 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. R133R) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00043 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000035 ( 0 hom. )

Consequence

ITPA
NM_033453.4 missense

Scores

Clinical Significance

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

Conservation

PhyloP100: 2.93

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 Likely_benign. Variant got -3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.061469793).

BS1

Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.000433 (66/152308) while in subpopulation AFR AF= 0.00152 (63/41568). AF 95% confidence interval is 0.00121. There are 0 homozygotes in gnomad4. There are 29 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ITPA	NM_033453.4 linkuse as main transcript	c.397A>G	p.Arg133Gly	missense_variant	6/8	ENST00000380113.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ITPA	ENST00000380113.8 linkuse as main transcript	c.397A>G	p.Arg133Gly	missense_variant	6/8	1	NM_033453.4	P1	Q9BY32-1

Frequencies

GnomAD3 genomes

AF:

0.000434

AC:

AN:

152190

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00152

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000193

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.000108

AC:

AN:

249244

Hom.:

AF XY:

0.0000740

AC XY:

AN XY:

135222

show subpopulations

Gnomad AFR exome

AF:

0.00156

Gnomad AMR exome

AF:

0.0000579

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000349

AC:

AN:

1460714

Hom.:

Cov.:

AF XY:

0.0000344

AC XY:

AN XY:

726768

show subpopulations

Gnomad4 AFR exome

AF:

0.00134

Gnomad4 AMR exome

AF:

0.0000224

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:

0.0000497

GnomAD4 genome

AF:

0.000433

AC:

AN:

152308

Hom.:

Cov.:

AF XY:

0.000389

AC XY:

AN XY:

74492

show subpopulations

Gnomad4 AFR

AF:

0.00152

Gnomad4 AMR

AF:

0.0000653

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000193

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.000473

Alfa

AF:

0.0000914

Hom.:

Bravo

AF:

0.000552

ESP6500AA

AF:

0.00204

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.000198

AC:

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

Invitae

Dec 18, 2023

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 133 of the ITPA protein (p.Arg133Gly). This variant is present in population databases (rs140777194, gnomAD 0.2%). 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: 574873). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. 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

Nov 13, 2022

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 -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.36

BayesDel_addAF

Benign

-0.28

BayesDel_noAF

Benign

-0.20

CADD

Benign

DANN

Benign

0.97

DEOGEN2

Pathogenic

0.89

D;.;.

Eigen

Benign

-0.44

Eigen_PC

Benign

-0.47

FATHMM_MKL

Benign

0.51

LIST_S2

Pathogenic

0.98

D;D;D

M_CAP

Benign

0.027

MetaRNN

Benign

0.061

T;T;T

MetaSVM

Benign

-0.43

MutationAssessor

Uncertain

2.4

M;.;.

MutationTaster

Benign

0.95

D;D;D

PrimateAI

Benign

0.47

PROVEAN

Uncertain

-4.3

D;D;D

REVEL

Benign

0.27

Sift

Benign

0.058

T;T;T

Sift4G

Benign

0.11

T;T;T

Polyphen

0.10

B;.;.

Vest4

0.67

MVP

0.18

MPC

0.78

ClinPred

0.15

GERP RS

-1.0

Varity_R

0.90

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

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