rs796053377

Positions:

• chr9-127682561-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_001032221.6(STXBP1):​c.1702+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: STXBP1 NM_001032221.6 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 9.86

Genes affected

STXBP1 (HGNC:11444): (syntaxin binding protein 1) This gene encodes a syntaxin-binding protein. The encoded protein appears to play a role in release of neurotransmitters via regulation of syntaxin, a transmembrane attachment protein receptor. Mutations in this gene have been associated with infantile epileptic encephalopathy-4. Alternatively spliced transcript variants have been described. [provided by RefSeq, Feb 2010]

STXBP1 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.6, offset of -37, new splice context is: gagGTgacc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-127682561-G-A is Pathogenic according to our data. Variant chr9-127682561-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 207444.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
STXBP1	NM_003165.6	c.1702+1G>A		splice_donor_variant, intron_variant		ENST00000373302.8	NP_003156.1
STXBP1	NM_001032221.6	c.1702+1G>A		splice_donor_variant, intron_variant		ENST00000373299.5	NP_001027392.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
STXBP1	ENST00000373302.8	c.1702+1G>A		splice_donor_variant, intron_variant		1	NM_003165.6	ENSP00000362399.3
STXBP1	ENST00000373299.5	c.1702+1G>A		splice_donor_variant, intron_variant		1	NM_001032221.6	ENSP00000362396.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Dec 04, 2019	Not observed in large population cohorts (Lek et al., 2016); Deletions involving coding exons in this gene are frequently reported as pathogenic, regardless of frame prediction (Stenson et al., 2014); This variant is associated with the following publications: (PMID: 29655203, 31344879, 30654231) -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen	Oct 23, 2020	- -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 10, 2020

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Thr574 amino acid residue in STXBP1. Other variant(s) that disrupt this residue have been observed in affected individuals (PMID: 21770924), suggesting that it is a clinically significant residue. As a result, variants that disrupt this residue are likely to be causative of disease. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has been observed to be de novo in an individual with clinical features of early infantile epileptic encephalopathy (Invitae). ClinVar contains an entry for this variant (Variation ID: 207444). This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in the last intron (intron 18) of the STXBP1 gene. While this is not anticipated to result in nonsense mediated decay, it likely alters RNA splicing and results in a disrupted protein product. -

STXBP1-associated neurodevelopmental disorder Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals

Jul 11, 2017

- -

Infantile epilepsy syndrome Pathogenic:1

Likely pathogenic, no assertion criteria provided

provider interpretation

GenomeConnect - Simons Searchlight

Dec 03, 2018

Submission from Simons Searchlight facilitated by GenomeConnect. Variant interpreted by the Simons Searchlight team most recently on 2018-12-03 and interpreted as Likely Pathogenic. Variant was initially reported on 2018-10-11 by GTR ID of laboratory name 500031. The reporting laboratory might also submit to ClinVar. -

Developmental and epileptic encephalopathy, 4 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Institute of Human Genetics, University of Leipzig Medical Center

Mar 12, 2019

This variant was identified as de novo (maternity and paternity confirmed). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.42
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
GERP RS		5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.99		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs796053377; hg19: chr9-130444840;