NM_000173.7:c.673T>C

Variant names:

• chr17-4933277-T-C
• rs1394634674
• NM_000173.7:c.673T>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_000173.7(GP1BA):​c.673T>C​(p.Cys225Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,694 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 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. C225S) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GP1BA NM_000173.7 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.25
• Publications: 5 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: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia
• congenital myasthenic syndrome 4B

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), PanelApp Australia
• 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 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-4933277-T-A is described in ClinVar as Pathogenic. ClinVar VariationId is 435347.Status of the report is reviewed_by_expert_panel, 3 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GP1BA	NM_000173.7	c.673T>C	p.Cys225Arg	missense_variant	Exon 2 of 2	ENST00000329125.6	NP_000164.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GP1BA	ENST00000329125.6	c.673T>C	p.Cys225Arg	missense_variant	Exon 2 of 2	1	NM_000173.7	ENSP00000329380.5
CHRNE	ENST00000649830.1	c.-888+1065A>G		intron_variant	Intron 1 of 10			ENSP00000496907.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461694 Hom.: 0 Cov.: 38 AF XY: 0.00000275 AC XY: 2 AN XY: 727126

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53400

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

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111858

Other (OTH) AF: 0.00 AC: 0 AN: 60372

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Nov 13, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: GP1BA c.673T>C (p.Cys225Arg) results in a non-conservative amino acid change in the encoded protein sequence. Four of four in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 249268 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.673T>C in individuals affected with Bernard-Soulier Syndrome, Type A2, Autosomal Dominant or Bernard-Soulier Syndrome, Type A1, Autosomal Recessive, and no experimental evidence demonstrating its impact on protein function have been reported. One submitter has cited clinical-significance assessments for this variant to ClinVar after 2014 and has classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Bernard Soulier syndrome Uncertain:1

Sep 28, 2018

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was determined to be of uncertain significance according to ACMG Guidelines, 2015 [PMID:25741868]. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.85	D;D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.42
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Benign	0.69	T;T
M_CAP	Uncertain	0.18	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Uncertain	0.059	D
MutationAssessor	Pathogenic	3.6	H;.
PhyloP100		6.3
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-12	D;.
REVEL	Pathogenic	0.65
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Vest4		0.96
MutPred		0.86		Gain of solvent accessibility (P = 0.0584);Gain of solvent accessibility (P = 0.0584);
MVP		0.89
MPC		0.54
ClinPred		1.0	D
GERP RS		4.8
Varity_R		0.93
gMVP		0.92
Mutation Taster		=30/70	disease causing

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: rs1394634674; hg19: chr17-4836572;