3-129061621-T-C

Position:

• chr3-129061621-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PVS1_Strong PM2 PP3

The NM_000174.5(GP9):​c.-13+2T>C variant causes a splice donor change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000294 in 679,266 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000029 (0 hom.)
• Consequence: GP9 NM_000174.5 splice_donor
• Scores: Splicing: ADA: 0.9885
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -1.08

Genes affected

GP9 (HGNC:4444): (glycoprotein IX platelet) This gene encodes a small membrane glycoprotein found on the surface of human platelets. It forms a 1-to-1 noncovalent complex with glycoprotein Ib, a platelet surface membrane glycoprotein complex that functions as a receptor for von Willebrand factor. The complete receptor complex includes noncovalent association of the alpha and beta subunits with the protein encoded by this gene and platelet glycoprotein V. Defects in this gene are a cause of Bernard-Soulier syndrome, also known as giant platelet disease. These patients have unusually large platelets and have a clinical bleeding tendency. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.2340824 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, max_spliceai. No scorers claiming Uncertain. Scorers claiming Benign: dbscSNV1_RF.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GP9	NM_000174.5	c.-13+2T>C		splice_donor_variant		ENST00000307395.5
GP9	XM_047447997.1	c.-12-107T>C		intron_variant
GP9	XM_005247374.4			downstream_gene_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GP9	ENST00000307395.5	c.-13+2T>C		splice_donor_variant		1	NM_000174.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000294 AC: 2 AN: 679266 Hom.: 0 Cov.: 9 AF XY: 0.00000279 AC XY: 1 AN XY: 358050

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: 0.00000454

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bernard Soulier syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Mar 05, 2018

The GP9 c.-13+2T>C variant occurs in a canonical splice site (donor) and is therefore predicted to disrupt or distort the normal gene product. It was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018) and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score for this variant, it could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene and cDNA change. No publications were found based on this search. Due to the potential impact of splice donor variants and the lack of clarifying evidence, this variant is classified as a variant of unknown significance but suspicious for pathogenicity for Bernard-Soulier syndrome. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.92
CADD	Benign	9.4
DANN	Benign	0.35

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.99
dbscSNV1_RF	Benign	0.51
SpliceAI score (max)		0.79		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.79		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1357144982; hg19: chr3-128780464;