20-3209599-C-T

Variant names:

• chr20-3209599-C-T
• rs2122274205
• NM_033453.4:c.48C>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Moderate BP6_Moderate

The NM_001324236.2(ITPA):​c.-293C>T variant causes a 5 prime UTR premature start codon gain change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,798 control chromosomes in the GnomAD database, with no homozygous occurrence. 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)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: ITPA NM_001324236.2 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 1.24
• 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: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.27).
• BP6: Variant 20-3209599-C-T is Benign according to our data. Variant chr20-3209599-C-T is described in ClinVar as Likely_benign. ClinVar VariationId is 1088509.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001324236.2. 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.48C>T	p.Asn16Asn	synonymous	Exon 1 of 8	NP_258412.1	A0A0S2Z3W7
	ITPA	NM_001324236.2		c.-293C>T		5_prime_UTR_premature_start_codon_gain	Exon 1 of 7	NP_001311165.1	Q8WWI0
	ITPA	NM_001424408.1		c.48C>T	p.Asn16Asn	synonymous	Exon 1 of 9	NP_001411337.1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ITPA	ENST00000380113.8	TSL:1 MANE Select	c.48C>T	p.Asn16Asn	synonymous	Exon 1 of 8	ENSP00000369456.3	Q9BY32-1
	ITPA	ENST00000399838.3	TSL:1	c.48C>T	p.Asn16Asn	synonymous	Exon 1 of 6	ENSP00000382732.3	Q9BY32-3
	ITPA	ENST00000455664.6	TSL:1	c.15+33C>T		intron	N/A	ENSP00000413282.1	Q9BY32-2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461798 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727202

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: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53374

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111970

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions as Germline

Significance: Likely benign

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	-	1	Inosine triphosphatase deficiency (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.27
CADD	Benign	14
DANN	Benign	0.93
PhyloP100		1.2
PromoterAI		-0.062	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.14		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: rs2122274205; hg19: chr20-3190245;