rs1554778417

chr9-127675802-A-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1_Moderate PM2 PP3_Strong PP5_Moderate

The NM_003165.6(STXBP1):c.1111-2A>G variant causes a splice acceptor 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: 32)
• Consequence: STXBP1 NM_003165.6 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 9.20

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 10 ACMG points.

• PVS1: Splicing variant, NOT destroyed by nmd, known LOF gene, truncates exone, which is 0.07615894 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.7, offset of -33, new splice context is: ttcctccacactgtcaccAGaga. Cryptic site results in inframe 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: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 9-127675802-A-G is Pathogenic according to our data. Variant chr9-127675802-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 461286.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
STXBP1	NM_001032221.6	c.1111-2A>G		splice_acceptor_variant		ENST00000373299.5
STXBP1	NM_003165.6	c.1111-2A>G		splice_acceptor_variant		ENST00000373302.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
STXBP1	ENST00000373299.5	c.1111-2A>G		splice_acceptor_variant		1	NM_001032221.6	A1
STXBP1	ENST00000373302.8	c.1111-2A>G		splice_acceptor_variant		1	NM_003165.6	P3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 25, 2020

This sequence change affects an acceptor splice site in intron 13 of the STXBP1 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. For these reasons, this variant has been classified as Pathogenic. Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in STXBP1 are known to be pathogenic (PMID: 20887364, 26384463). 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 in individual(s) with STXBP1-related conditions (PMID: 30488659, Invitae). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 461286). This variant is not present in population databases (ExAC no frequency). -

Developmental and epileptic encephalopathy, 4 Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Wu Jinyu Laboratory, Institute of Genomic Medicine, Wenzhou Medical University

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.35
Cadd	Pathogenic	33
Dann	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D;D
GERP RS		5.6

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.89		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.31		Position offset: -31
DS_AL_spliceai		0.89		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554778417; hg19: chr9-130438081;