rs1555549041

Variant names:

• chr17-4932706-CA-C
• rs1555549041
• NM_000173.7:c.104delA

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PVS1_Strong PS3_Supporting PP4 PM2_Supporting PM3

This summary comes from the ClinGen Evidence Repository: The c.104del (p.Lys35ArgfsTer4) variant in GP1BA is a frameshift variant that may cause loss of function of the protein, however it is predicted to escape nonsense mediated decay and remove >10% of the protein (PVS1_Strong). At least one patient (Patient GA in PMID:8950770) with this variant had aggregation absent for ristocetin and present for all other agonists, which is highly specific for Bernard-Soulier syndrome (PP4). They also had thrombocytopenia, giant platelets, and life-long severe bleeding, including recurrent bruising and prolonged bleeding time. This variant has been detected in at least 2 probands with Bernard-Soulier syndrome (PMID:8950770 and 36507135). These individuals were both homozygous for the variant (PM3). Surface expression of GP1A measured by flow cytometry in mouse L cells transiently co-transfected with c.104del (p.Lys35ArgfsTer4) variant GP1A and wild type GP1B-GP9 showed undetectable expression at 0% WT levels, indicating that this variant impacts protein function (PMID:8950770, PS3_supporting). The Grpmax Filtering allele frequency in gnomAD v4.1.0 is 3.000e-7 (based on 2/1179868 alleles) in the European non Finnish population, which is lower than the ClinGen PD VCEP threshold (<0.0001114; PM2_Supporting). In summary, this variant meets the criteria to be classified as Likely Pathogenic for autosomal recessive Bernard-Soulier syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen PD VCEP: PVS1_Strong, PP4, PM2_Supporting, PM3, and PS3_Supporting. LINK:https://erepo.genome.network/evrepo/ui/classification/CA658798681/MONDO:0009276/079

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GP1BA NM_000173.7 frameshift
• Clinical Significance: Likely pathogenic reviewed by expert panel P:4
• Conservation: PhyloP100: 0.00100
• Publications: 1 publications found

Genes affected

GP1BA (HGNC:4439): (glycoprotein Ib platelet subunit alpha) Glycoprotein Ib (GP Ib) is a platelet surface membrane glycoprotein composed of a heterodimer, an alpha chain and a beta chain, that is linked by disulfide bonds. The Gp Ib functions as a receptor for von Willebrand factor (VWF). The complete receptor complex includes noncovalent association of the alpha and beta subunits with platelet glycoprotein IX and platelet glycoprotein V. The binding of the GP Ib-IX-V complex to VWF facilitates initial platelet adhesion to vascular subendothelium after vascular injury, and also initiates signaling events within the platelet that lead to enhanced platelet activation, thrombosis, and hemostasis. This gene encodes the alpha subunit. Mutations in this gene result in Bernard-Soulier syndromes and platelet-type von Willebrand disease. The coding region of this gene is known to contain a polymophic variable number tandem repeat (VNTR) domain that is associated with susceptibility to nonarteritic anterior ischemic optic neuropathy. [provided by RefSeq, Oct 2013]

CHRNE (HGNC:1966): (cholinergic receptor nicotinic epsilon subunit) Acetylcholine receptors at mature mammalian neuromuscular junctions are pentameric protein complexes composed of four subunits in the ratio of two alpha subunits to one beta, one epsilon, and one delta subunit. The acetylcholine receptor changes subunit composition shortly after birth when the epsilon subunit replaces the gamma subunit seen in embryonic receptors. Mutations in the epsilon subunit are associated with congenital myasthenic syndrome. [provided by RefSeq, Sep 2009]

CHRNE Gene-Disease associations (from GenCC):

• congenital myasthenic syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: Illumina
• congenital myasthenic syndrome 4A

  Inheritance: AD, AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• congenital myasthenic syndrome 4B

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• congenital myasthenic syndrome 4C

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• postsynaptic congenital myasthenic syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PS3: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.
• PM3: For more information check the summary or visit ClinGen Evidence Repository.
• PP4: For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000173.7. 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
	GP1BA	NM_000173.7	MANE Select	c.104delA	p.Lys35ArgfsTer4	frameshift	Exon 2 of 2	NP_000164.5

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GP1BA	ENST00000329125.6	TSL:1 MANE Select	c.104delA	p.Lys35ArgfsTer4	frameshift	Exon 2 of 2	ENSP00000329380.5	P07359
	CHRNE	ENST00000649830.1		c.-888+1635delT		intron	N/A	ENSP00000496907.1	A0A3B3IRM1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461698 Hom.: 0 Cov.: 37 AF XY: 0.00000138 AC XY: 1 AN XY: 727132

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: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53402

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111860

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
2	-	-	Bernard Soulier syndrome (2)
2	-	-	not provided (2)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.0010
Mutation Taster		=2/198	disease causing (ClinVar)

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: rs1555549041; hg19: chr17-4836001;