chr17-44372424-C-T

Position:

• chr17-44372424-C-T

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PP4_Strong PM2_Supporting PM3_Supporting PVS1_Strong

This summary comes from the ClinGen Evidence Repository: The NM_000419.5(ITGA2B):c.3061-1G>A occurs within the canonical splice acceptor site of intron 29. It is predicted to cause skipping of biologically-relevant-exon 29, resulting in the in-frame deletion of 39 amino acids (3.7% of the protein) of the transmembrane region, which is considered a critical region by the PD-EP (PVS1_strong). At least one patient (GT31 in PMID:25728920) with this variant displayed mucocutaneous bleeding and impaired aggregation with all agonists except ristocetin, which is highly specific for Glanzmann thrombasthenia. Additionally, αIIbβ3 surface expression was reduced to <5%, as measured by flow cytometry (PP4_strong). GT31 is compound heterozygous for c.1771dup (classified Pathogenic by the PD-EP) and c.3061-1G>A (PM3_supporting). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). In summary this variant meets criteria to be classified as Pathogenic for autosomal recessive Glanzmann Thrombasthenia based on the ACMG/AMP criteria applied, as specified by the ClinGen PD VCEP: PVS1_strong, PP4_strong, PM2_supporting, PM3_supporting. (VCEP specifications version 2.1). LINK:https://erepo.genome.network/evrepo/ui/classification/CA399787972/MONDO:0100326/011

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: ITGA2B NM_000419.5 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic reviewed by expert panel P:1
• Conservation: PhyloP100: 4.06

Genes affected

ITGA2B (HGNC:6138): (integrin subunit alpha 2b) This gene encodes a member of the integrin alpha chain family of proteins. The encoded preproprotein is proteolytically processed to generate light and heavy chains that associate through disulfide linkages to form a subunit of the alpha-IIb/beta-3 integrin cell adhesion receptor. This receptor plays a crucial role in the blood coagulation system, by mediating platelet aggregation. Mutations in this gene are associated with platelet-type bleeding disorders, which are characterized by a failure of platelet aggregation, including Glanzmann thrombasthenia. [provided by RefSeq, Jan 2016]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ITGA2B	NM_000419.5	c.3061-1G>A		splice_acceptor_variant		ENST00000262407.6
ITGA2B	XM_011524749.2	c.3112-1G>A		splice_acceptor_variant
ITGA2B	XM_011524750.2	c.3097-1G>A		splice_acceptor_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ITGA2B	ENST00000262407.6	c.3061-1G>A		splice_acceptor_variant		1	NM_000419.5	P1
ITGA2B	ENST00000587295.5	c.254-1G>A		splice_acceptor_variant		3
ITGA2B	ENST00000648408.1	c.2375-1G>A		splice_acceptor_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461822 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727206

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: reviewed by expert panel

Submissions by phenotype

Glanzmann thrombasthenia Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Platelet Disorders Variant Curation Expert Panel, ClinGen

Aug 05, 2022

The NM_000419.5(ITGA2B):c.3061-1G>A occurs within the canonical splice acceptor site of intron 29. It is predicted to cause skipping of biologically-relevant-exon 29, resulting in the in-frame deletion of 39 amino acids (3.7% of the protein) of the transmembrane region, which is considered a critical region by the PD-EP (PVS1_strong). At least one patient (GT31 in PMID: 25728920) with this variant displayed mucocutaneous bleeding and impaired aggregation with all agonists except ristocetin, which is highly specific for Glanzmann thrombasthenia. Additionally, αIIbβ3 surface expression was reduced to <5%, as measured by flow cytometry (PP4_strong). GT31 is compound heterozygous for c.1771dup (classified Pathogenic by the PD-EP) and c.3061-1G>A (PM3_supporting). This variant is absent from gnomAD v2.1.1 (PM2_Supporting). In summary this variant meets criteria to be classified as Pathogenic for autosomal recessive Glanzmann Thrombasthenia based on the ACMG/AMP criteria applied, as specified by the ClinGen PD VCEP: PVS1_strong, PP4_strong, PM2_supporting, PM3_supporting. (VCEP specifications version 2.1). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.050
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	0.78
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.95	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.5

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.56		Position offset: -2
DS_AL_spliceai		0.98		Position offset: -1

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr17-42449792; COSMIC: COSV99288726; COSMIC: COSV99288726;