NM_000407.5:c.137G>C

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 1P and 2B. PP2BP4_Moderate

The NM_000407.5(GP1BB):c.137G>C(p.Trp46Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000783 in 1,532,362 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000080 ( 0 hom. )

Consequence

GP1BB
NM_000407.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: -0.520

Publications

3 publications found

Variant links:

Genes affected

GP1BB (HGNC:4440): (glycoprotein Ib platelet subunit beta) Platelet glycoprotein Ib (GPIb) is a heterodimeric transmembrane protein consisting of a disulfide-linked 140 kD alpha chain and 22 kD beta chain. It is part of the GPIb-V-IX system that constitutes the receptor for von Willebrand factor (VWF), and mediates platelet adhesion in the arterial circulation. GPIb alpha chain provides the VWF binding site, and GPIb beta contributes to surface expression of the receptor and participates in transmembrane signaling through phosphorylation of its intracellular domain. Mutations in the GPIb beta subunit have been associated with Bernard-Soulier syndrome, velocardiofacial syndrome and giant platelet disorder. The 206 amino acid precursor of GPIb beta is synthesized from a 1.0 kb mRNA expressed in plateletes and megakaryocytes. A 411 amino acid protein arising from a longer, unspliced transcript in endothelial cells has been described; however, the authenticity of this product has been questioned. Yet another less abundant GPIb beta mRNA species of 3.5 kb, expressed in nonhematopoietic tissues such as endothelium, brain and heart, was shown to result from inefficient usage of a non-consensus polyA signal in the neighboring upstream gene (SEPT5, septin 5). In the absence of polyadenylation from its own imperfect site, the SEPT5 gene produces read-through transcripts that use the consensus polyA signal of this gene. [provided by RefSeq, Dec 2010]

GP1BB links:

ENSG00000284874 (HGNC:):

ENSG00000284874 links:

SEPTIN5 (HGNC:9164): (septin 5) This gene is a member of the septin gene family of nucleotide binding proteins, originally described in yeast as cell division cycle regulatory proteins. Septins are highly conserved in yeast, Drosophila, and mouse and appear to regulate cytoskeletal organization. Disruption of septin function disturbs cytokinesis and results in large multinucleate or polyploid cells. This gene is mapped to 22q11, the region frequently deleted in DiGeorge and velocardiofacial syndromes. A translocation involving the MLL gene and this gene has also been reported in patients with acute myeloid leukemia. Alternative splicing results in multiple transcript variants. The presence of a non-consensus polyA signal (AACAAT) in this gene also results in read-through transcription into the downstream neighboring gene (GP1BB; platelet glycoprotein Ib), whereby larger, non-coding transcripts are produced. [provided by RefSeq, Dec 2010]

SEPTIN5 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 14 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 0.45873 (below the threshold of 3.09). Trascript score misZ: -2.9917 (below the threshold of 3.09). GenCC associations: The gene is linked to Bernard-Soulier syndrome, autosomal dominant macrothrombocytopenia.

BP4

Computational evidence support a benign effect (MetaRNN=0.21707323).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000407.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
GP1BB	NM_000407.5	MANE Select	c.137G>C	p.Trp46Ser	missense	Exon 2 of 2	NP_000398.1
SEPT5-GP1BB	NR_037611.1		n.3877G>C		non_coding_transcript_exon	Exon 12 of 12
SEPT5-GP1BB	NR_037612.1		n.2381G>C		non_coding_transcript_exon	Exon 12 of 12

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
GP1BB	ENST00000366425.4	TSL:1 MANE Select	c.137G>C	p.Trp46Ser	missense	Exon 2 of 2	ENSP00000383382.2
ENSG00000284874	ENST00000431044.5	TSL:1	n.*1222G>C		non_coding_transcript_exon	Exon 12 of 12	ENSP00000399685.1
ENSG00000284874	ENST00000455843.5	TSL:1	n.*1222G>C		non_coding_transcript_exon	Exon 12 of 12	ENSP00000391731.1

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152090

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000753

AC:

AN:

132770

AF XY:

0.0000135

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000187

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000797

AC:

AN:

1380272

Hom.:

Cov.:

AF XY:

0.00000879

AC XY:

AN XY:

682602

show subpopulations

African (AFR)

AF:

0.000171

AC:

AN:

29306

American (AMR)

AF:

0.00

AC:

AN:

36412

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24726

East Asian (EAS)

AF:

0.00

AC:

AN:

34488

South Asian (SAS)

AF:

0.00

AC:

AN:

78438

European-Finnish (FIN)

AF:

0.00

AC:

AN:

35338

Middle Eastern (MID)

AF:

0.000580

AC:

AN:

5170

European-Non Finnish (NFE)

AF:

0.00000185

AC:

AN:

1078934

Other (OTH)

AF:

0.0000174

AC:

AN:

57460

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.480

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00000658

AC:

AN:

152090

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74302

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41434

American (AMR)

AF:

0.00

AC:

AN:

15276

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5176

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10588

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67992

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Jul 31, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.137G>C (p.W46S) alteration is located in exon 2 (coding exon 2) of the GP1BB gene. This alteration results from a G to C substitution at nucleotide position 137, causing the tryptophan (W) at amino acid position 46 to be replaced by a serine (S). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.11

BayesDel_addAF

Benign

-0.14

BayesDel_noAF

Benign

-0.42

CADD

Benign

(source)

DANN

Benign

0.74

DEOGEN2

Benign

0.33

Eigen

Benign

-1.3

Eigen_PC

Benign

-1.3

FATHMM_MKL

Benign

0.32

LIST_S2

Benign

0.36

M_CAP

Pathogenic

0.83

MetaRNN

Benign

0.22

MetaSVM

Benign

-0.96

MutationAssessor

Benign

-0.69

PhyloP100

-0.52

PROVEAN

Benign

-1.0

REVEL

Benign

0.19

Sift

Benign

0.69

Sift4G

Benign

0.76

Polyphen

0.0050

Vest4

0.14

MutPred

0.53

Gain of disorder (P = 6e-04)

MVP

0.61

MPC

1.1

ClinPred

0.016

GERP RS

-4.7

PromoterAI

-0.061

Neutral

(source)

RBP_binding_hub_radar

0.92

RBP_regulation_power_radar

2.7

Varity_R

0.42

gMVP

0.35

Mutation Taster

=93/7

polymorphism

(source)

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over