9-127612408-C-T

Variant names:

• chr9-127612408-C-T
• rs1838427784
• NM_003165.6:c.5C>T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP2

The NM_001032221.6(STXBP1):​c.5C>T​(p.Ala2Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 30)
• Consequence: STXBP1 NM_001032221.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.00700

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 Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the STXBP1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 106 curated pathogenic missense variants (we use a threshold of 10). The gene has 79 curated benign missense variants. Gene score misZ: 4.263 (above the threshold of 3.09). Trascript score misZ: 5.8379 (above the threshold of 3.09). GenCC associations: The gene is linked to intellectual disability, autosomal dominant non-syndromic intellectual disability, Dravet syndrome, undetermined early-onset epileptic encephalopathy, autism spectrum disorder, developmental and epileptic encephalopathy, West syndrome, atypical Rett syndrome, developmental and epileptic encephalopathy, 4.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
STXBP1	NM_003165.6	c.5C>T	p.Ala2Val	missense_variant	Exon 1 of 20	ENST00000373302.8	NP_003156.1
STXBP1	NM_001032221.6	c.5C>T	p.Ala2Val	missense_variant	Exon 1 of 19	ENST00000373299.5	NP_001027392.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
STXBP1	ENST00000373302.8	c.5C>T	p.Ala2Val	missense_variant	Exon 1 of 20	1	NM_003165.6	ENSP00000362399.3
STXBP1	ENST00000373299.5	c.5C>T	p.Ala2Val	missense_variant	Exon 1 of 19	1	NM_001032221.6	ENSP00000362396.2

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 30

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Uncertain:1

Feb 18, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine with valine at codon 2 of the STXBP1 protein (p.Ala2Val). The alanine residue is weakly conserved and there is a small physicochemical difference between alanine and valine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with STXBP1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
BayesDel_addAF	Benign	-0.026	T
BayesDel_noAF	Benign	-0.28
CADD	Uncertain	25
DANN	Pathogenic	1.0
DEOGEN2	Benign	0.023	.;T;.;T;.
Eigen	Uncertain	0.21
Eigen_PC	Benign	0.11
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Uncertain	0.94	D;D;D;D;.
M_CAP	Pathogenic	0.99	D
MetaRNN	Uncertain	0.48	T;T;T;T;T
MetaSVM	Benign	-0.29	T
MutationAssessor	Uncertain	2.3	M;.;.;M;.
PrimateAI	Pathogenic	0.86	D
PROVEAN	Benign	-0.81	N;.;.;N;.
REVEL	Benign	0.23
Sift	Uncertain	0.0030	D;.;.;D;.
Sift4G	Uncertain	0.0070	D;.;.;D;.
Polyphen		0.98	D;.;.;D;.
Vest4		0.12
MutPred		0.31		Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);
MVP		0.54
MPC		1.6
ClinPred		0.68	D
GERP RS		2.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.16
gMVP		0.63

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

LitVar

Other links and lift over

dbSNP: rs1838427784; hg19: chr9-130374687;