17-44372423-C-A

Position:

• chr17-44372423-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000419.5(ITGA2B):​c.3061G>T​(p.Val1021Phe) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,818 control chromosomes in the GnomAD database, with no homozygous occurrence. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V1021A) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: ITGA2B NM_000419.5 missense, splice_region
• Scores: Splicing: ADA: 0.9741
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.147

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 Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a chain Integrin alpha-IIb light chain, form 1 (size 148) in uniprot entity ITA2B_HUMAN there are 8 pathogenic changes around while only 2 benign (80%) in NM_000419.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ITGA2B	NM_000419.5	c.3061G>T	p.Val1021Phe	missense_variant, splice_region_variant	30/30	ENST00000262407.6
ITGA2B	XM_011524749.2	c.3112G>T	p.Val1038Phe	missense_variant, splice_region_variant	29/29
ITGA2B	XM_011524750.2	c.3097G>T	p.Val1033Phe	missense_variant, splice_region_variant	29/29

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ITGA2B	ENST00000262407.6	c.3061G>T	p.Val1021Phe	missense_variant, splice_region_variant	30/30	1	NM_000419.5	P1
ITGA2B	ENST00000648408.1	c.2377G>T	p.Val793Phe	missense_variant, splice_region_variant	25/25
ITGA2B	ENST00000587295.5	c.256G>T	p.Val86Phe	missense_variant, splice_region_variant	3/3	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251170 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135818

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000881

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461818 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727204

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glanzmann thrombasthenia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 14, 2023

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. This variant has not been reported in the literature in individuals affected with ITGA2B-related conditions. This variant is present in population databases (rs755197006, gnomAD 0.0009%). This sequence change replaces valine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 1021 of the ITGA2B protein (p.Val1021Phe). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.16
BayesDel_addAF	Uncertain	0.028	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	21
DANN	Uncertain	0.98
DEOGEN2	Benign	0.39	T
Eigen	Benign	-0.54
Eigen_PC	Benign	-0.64
FATHMM_MKL	Benign	0.17	N
LIST_S2	Benign	0.71	T
M_CAP	Uncertain	0.11	D
MetaRNN	Uncertain	0.58	D
MetaSVM	Benign	-0.44	T
MutationAssessor	Benign	1.4	L
MutationTaster	Benign	0.99	N;N
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-1.5	N
REVEL	Uncertain	0.50
Sift	Benign	0.092	T
Sift4G	Benign	0.14	T
Polyphen		0.81	P
Vest4		0.28
MutPred		0.61		Loss of ubiquitination at K1025 (P = 0.1079);
MVP		0.78
MPC		0.81
ClinPred		0.22	T
GERP RS		2.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.19
gMVP		0.60

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.79
SpliceAI score (max)		0.090		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs755197006; hg19: chr17-42449791;