rs1554776853

Positions:

• chr9-127660107-CTG-C

Variant summary

Our verdict is Pathogenic. Variant got 20 ACMG points: 20P and 0B. PVS1 PM2 PP3_Moderate PP5_Very_Strong

The NM_003165.6(STXBP1):​c.325+2_325+3del variant causes a splice donor, coding sequence change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: STXBP1 NM_003165.6 splice_donor, coding_sequence
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.65

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]

ACMG classification

Verdict is Pathogenic. Variant got 20 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 4.9, offset of 38, new splice context is: cagGTtagc. 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
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 9-127660107-CTG-C is Pathogenic according to our data. Variant chr9-127660107-CTG-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 496686.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
STXBP1	NM_001032221.6	c.325+2_325+3del		splice_donor_variant, coding_sequence_variant	5/19	ENST00000373299.5
STXBP1	NM_003165.6	c.325+2_325+3del		splice_donor_variant, coding_sequence_variant	5/20	ENST00000373302.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
STXBP1	ENST00000373299.5	c.325+2_325+3del		splice_donor_variant, coding_sequence_variant	5/19	1	NM_001032221.6	A1
STXBP1	ENST00000373302.8	c.325+2_325+3del		splice_donor_variant, coding_sequence_variant	5/20	1	NM_003165.6	P3

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 4 Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals	Nov 26, 2018	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Equipe Genetique des Anomalies du Developpement, Université de Bourgogne	Nov 01, 2016	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Nov 01, 2022

Canonical splice site variant predicted to result in a null allele in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.69		Position offset: 41
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: rs1554776853; hg19: chr9-130422386;