20-3213219-A-G

Variant names:

• chr20-3213219-A-G
• rs538432614
• NM_033453.4:c.117A>G

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 2P and 7B. PM2 BP4_Strong BP6_Moderate BP7

The NM_033453.4(ITPA):​c.117A>G​(p.Lys39Lys) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: ITPA NM_033453.4 synonymous
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 1.11
• 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

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.56).
• BP6: Variant 20-3213219-A-G is Benign according to our data. Variant chr20-3213219-A-G is described in ClinVar as Likely_benign. ClinVar VariationId is 1140799.Status of the report is criteria_provided_single_submitter, 1 stars.
• BP7: Synonymous conserved (PhyloP=1.12 with no splicing effect.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITPA	NM_033453.4	MANE Select	c.117A>G	p.Lys39Lys	synonymous	Exon 2 of 8	NP_258412.1
	ITPA	NM_001424408.1		c.117A>G	p.Lys39Lys	synonymous	Exon 2 of 9	NP_001411337.1
	ITPA	NM_001424409.1		c.243A>G	p.Lys81Lys	synonymous	Exon 3 of 9	NP_001411338.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITPA	ENST00000380113.8	TSL:1 MANE Select	c.117A>G	p.Lys39Lys	synonymous	Exon 2 of 8	ENSP00000369456.3
	ITPA	ENST00000455664.6	TSL:1	c.66A>G	p.Lys22Lys	synonymous	Exon 2 of 8	ENSP00000413282.1
	ITPA	ENST00000399838.3	TSL:1	c.67-766A>G		intron	N/A	ENSP00000382732.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inosine triphosphatase deficiency Benign:1

Aug 06, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.56
CADD	Benign	11
DANN	Benign	0.64
PhyloP100		1.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.13		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: rs538432614; hg19: chr20-3193865;