chr20-3223304-T-C

Variant names:

• chr20-3223304-T-C
• rs2236206
• NM_033453.4:c.489-62T>C

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_033453.4(ITPA):​c.489-62T>C variant causes a intron 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: ITPA NM_033453.4 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -1.42
• Publications: 7 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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.84).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ITPA	NM_033453.4	c.489-62T>C		intron_variant	Intron 7 of 7	ENST00000380113.8	NP_258412.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ITPA	ENST00000380113.8	c.489-62T>C		intron_variant	Intron 7 of 7	1	NM_033453.4	ENSP00000369456.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1056874 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 539774

African (AFR) AF: 0.00 AC: 0 AN: 25606

American (AMR) AF: 0.00 AC: 0 AN: 39428

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 23358

East Asian (EAS) AF: 0.00 AC: 0 AN: 36206

South Asian (SAS) AF: 0.00 AC: 0 AN: 74794

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 47546

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5050

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 757716

Other (OTH) AF: 0.00 AC: 0 AN: 47170

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 2882

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.84
CADD	Benign	1.2
DANN	Benign	0.86
PhyloP100		-1.4

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

Other links and lift over

dbSNP: rs2236206; hg19: chr20-3203950;