NM_033453.4:c.49G>A

Variant names:

• chr20-3209600-G-A
• rs754960642
• NM_033453.4:c.49G>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_033453.4(ITPA):​c.49G>A​(p.Ala17Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,784 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A17S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ITPA NM_033453.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.34
• Publications: 0 publications found

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

ENSG00000289494 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.39848262).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_033453.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITPA	NM_033453.4	MANE Select	c.49G>A	p.Ala17Thr	missense	Exon 1 of 8	NP_258412.1	A0A0S2Z3W7
	ITPA	NM_001424408.1		c.49G>A	p.Ala17Thr	missense	Exon 1 of 9	NP_001411337.1
	ITPA	NM_001267623.2		c.49G>A	p.Ala17Thr	missense	Exon 1 of 6	NP_001254552.1	Q9BY32-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITPA	ENST00000380113.8	TSL:1 MANE Select	c.49G>A	p.Ala17Thr	missense	Exon 1 of 8	ENSP00000369456.3	Q9BY32-1
	ITPA	ENST00000399838.3	TSL:1	c.49G>A	p.Ala17Thr	missense	Exon 1 of 6	ENSP00000382732.3	Q9BY32-3
	ITPA	ENST00000455664.6	TSL:1	c.15+34G>A		intron	N/A	ENSP00000413282.1	Q9BY32-2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461784 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727184

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53364

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111966

Other (OTH) AF: 0.00 AC: 0 AN: 60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Uncertain	0.035	T
BayesDel_noAF	Benign	-0.19
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.77	D
Eigen	Benign	-0.098
Eigen_PC	Benign	-0.0050
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.94	D
M_CAP	Benign	0.035	D
MetaRNN	Benign	0.40	T
MetaSVM	Benign	-0.57	T
MutationAssessor	Pathogenic	3.0	M
PhyloP100		4.3
PrimateAI	Uncertain	0.62	T
PROVEAN	Uncertain	-2.7	D
REVEL	Uncertain	0.42
Sift	Benign	0.052	T
Sift4G	Benign	0.12	T
Polyphen		0.079	B
Vest4		0.47
MutPred		0.47		Loss of MoRF binding (P = 0.0954)
MVP		0.57
MPC		0.31
ClinPred		0.99	D
GERP RS		3.5
PromoterAI		-0.051	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.76
gMVP		0.081
Mutation Taster		=30/70	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs754960642; hg19: chr20-3190246;