9-127675910-G-T

Variant names:

• chr9-127675910-G-T
• rs886041246
• NM_003165.6:c.1217G>T

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001032221.6(STXBP1):​c.1217G>T​(p.Arg406Leu) variant causes a missense 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R406C) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: STXBP1 NM_001032221.6 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.15

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 17 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-127675909-C-T is described in Lovd as [Pathogenic].
• 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.977
• PP5: Variant 9-127675910-G-T is Pathogenic according to our data. Variant chr9-127675910-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 419223.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
STXBP1	NM_003165.6	c.1217G>T	p.Arg406Leu	missense_variant	Exon 14 of 20	ENST00000373302.8	NP_003156.1
STXBP1	NM_001032221.6	c.1217G>T	p.Arg406Leu	missense_variant	Exon 14 of 19	ENST00000373299.5	NP_001027392.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
STXBP1	ENST00000373302.8	c.1217G>T	p.Arg406Leu	missense_variant	Exon 14 of 20	1	NM_003165.6	ENSP00000362399.3
STXBP1	ENST00000373299.5	c.1217G>T	p.Arg406Leu	missense_variant	Exon 14 of 19	1	NM_001032221.6	ENSP00000362396.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Mar 13, 2025

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are a common cause of disease and they are underrepresented in the general population; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 29896790, 35982159, 33057194) -

Developmental and epileptic encephalopathy, 4 Pathogenic:1

Feb 14, 2020

Laboratory of Inherited Metabolic Diseases, Research centre for medical genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Benign	0.29	.;T;.;D;.;T;D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D;.;D;D;D;D;D
M_CAP	Pathogenic	0.75	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.3	.;.;M;.;.;.;M
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-6.9	.;.;D;.;.;.;D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	.;.;D;.;.;.;D
Sift4G	Pathogenic	0.0010	.;.;D;.;.;.;D
Polyphen		1.0	.;.;D;.;.;.;D
Vest4		0.97, 0.97
MutPred		0.83		.;.;Loss of sheet (P = 0.0142);Loss of sheet (P = 0.0142);Loss of sheet (P = 0.0142);.;Loss of sheet (P = 0.0142);
MVP		0.95
MPC		1.6
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.92
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.080		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: rs886041246; hg19: chr9-130438189;