STX1A

Chr 7

syntaxin 1A

Also known as: HPC-1, P35-1, STX1, SYN1A

This protein is a key component of the SNARE complex that mediates calcium-dependent neurotransmitter release and synaptic vesicle fusion at presynaptic terminals. Mutations cause early infantile epileptic encephalopathy with autosomal dominant inheritance, typically presenting with seizures beginning in infancy and developmental delays. The gene is highly constrained against loss-of-function variants, reflecting its essential role in synaptic transmission.

OMIMResearchSummary from RefSeq, UniProt
MultiplemechanismLOEUF 0.29
Clinical SummarySTX1A
Population Constraint (gnomAD)
Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 0.98). One damaged copy is likely sufficient to cause disease.
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Clinical Trials
1 active or recruiting trial — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

LoF intolerant — likely haploinsufficient
LoF Constraint
0.29LOEUF
pLI 0.979
Z-score 3.50
OE 0.06 (0.020.29)
Highly constrained

Highly LoF-intolerant (top ~10% of genes)

Missense Constraint
2.40Z-score
OE missense 0.51 (0.430.61)
98 obs / 191.4 exp
Mild constraint

Moderately missense-constrained (top ~2.5%)

Observed / Expected Ratios
LoF OE0.06 (0.020.29)
00.351.4
Missense OE0.51 (0.430.61)
00.61.4
Synonymous OE0.86
01.21.6
LoF obs/exp: 1 / 16.2Missense obs/exp: 98 / 191.4Syn Z: 0.95
Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗
limitedSTX1A-related neurodevelopmental disorder without epilepsyOTHERAR
moderateSTX1A-related neurodevelopmental disorder with epilepsyOTHERAD
DN
0.6648th %ile
GOF
0.6052th %ile
LOF
0.4825th %ile

This gene has evidence for multiple mechanisms of pathogenicity (loss-of-function and dominant-negative). The Badonyi & Marsh model scores dominant-negative highest among its predictions, but genomic evidence (constraint, ClinVar variant spectrum, and literature) most strongly supports loss-of-function (haploinsufficiency). Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

LOFLOEUF 0.29
DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312. Mechanism ranking also informed by gnomAD constraint, ClinVar, and ClinGen data.

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

STX1A · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

3D Protein StructureAlphaFold
Clinical Literature
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