RARE DISEASE
STXBP1-related encephalopathy
STXBP1-related encephalopathy
STXBP1-related encephalopathy
Drug discovery
2
drugs
With orphan designations
Overview
STXBP1-related encephalopathy is a rare genetic neurodevelopmental disorder caused by pathogenic variants in the STXBP1 gene, which disrupts synaptic neurotransmitter release. It presents with severe intellectual disability, developmental delay, and early-onset epilepsy (85-90% of cases), often featuring infantile spasms, focal seizures, or refractory seizures. Motor impairments (hypotonia, ataxia, spasticity) and autism spectrum features are common. Phenotypic variability exists, with seizure trajectories ranging from remission to lifelong refractory epilepsy [1][2][14].
Therapies
Antiseizure medications (e.g., levetiracetam, phenobarbital) and ketogenic diet for seizure control; 25% have refractory epilepsy [2][5].
Multidisciplinary care (physical, occupational, speech therapy) for neurodevelopmental support [12][17].
Emerging therapies: Gene replacement (CAP-002 in preclinical trials) and STXBP1 protein-enhancing agents (e.g., 4-phenylbutyrate under investigation) [3][7].
Categories: rare genetic diseases, rare neurological diseases
Research Papers
33 drug discovery papers about STXBP1-related encephalopathy, with 2 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
33 drug discovery papers about STXBP1-related encephalopathy, with 2 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-06-29 | Monogenic epilepsies exhibit distinct sleep endophenotypes
Abstract Monogenic epilepsies are 1.6 times more likely to be treatment-resistant compared to other epilepsies, emphasizing the need for additional therapeutic strategies. Sleep dysfunction beyond sleep-related breathing disorders is common yet insufficiently characterized and treated in monogenic epilepsies. We therefore sought to study sleep phenotypes across these epilepsies, examine associations with seizure severity, and assess the diagnostic rate of sleep disorders. From 2,519 individuals enrolled in the Epilepsy Genetics Research Project at Children’s Hospital of Philadelphia, we identified the monogenic epilepsies most frequently associated with sleep-related diagnoses, yielding 252 individuals across nine genetic diagnoses ( STXBP1 , n = 79; SCN1A , n = 57; SCN2A , n = 34; KCNQ2 , n = 21; SLC6A1 , n = 14; SYNGAP1 , n = 13; WDR45 , n = 13; KCNT1 , n = 11; PCDH19 , n = 10). Monogenic epilepsies exhibited distinct sleep endophenotypes, including insomnia, parasomnia, and sleep-related movement disorders in SCN1A -related disorders; frequent epileptiform discharges in sleep with insomnia symptoms in SCN2A -related disorders; sleep dysfunction restricted to the developmental and epileptic encephalopathy subtype in KCNQ2 -related disorders; and insomnia without nocturnal seizure involvement in SYNGAP1 -related disorders. Formal sleep diagnoses were present in only 25% of individuals (63/252), yet 58% (145/252) reported sleep difficulties, suggesting substantial underdiagnosis. Persistent seizures were associated with higher odds of sleep disorder diagnoses ( OR 2.87, 95% CrI 1.57–5.36), disrupted sleep architecture ( OR 2.06, 95% CrI 1.08–4.16), nocturnal seizures ( OR 4.47, 95% CrI 2.50–8.28), hypersomnolence ( OR 2.38, 95% CrI 1.27–4.58) and insomnia ( OR 1.80, 95% CrI 1.06–3.05). Neuropsychiatric comorbidities were independently associated with sleep burden after adjustment for seizure severity ( OR 2.49, 95% CrI 1.40–4.49). We find that monogenic epilepsies exhibit distinct, gene-specific sleep endophenotypes that are underdiagnosed. Treating sleep difficulties beyond obstructive sleep apnoea may improve seizure control and developmental outcomes, highlighting the need for timely diagnosis of co-occurring sleep disorders.
2026-06-09 | CRISPR-mediated Stxbp1 gene activation ameliorates epileptic and aggressive phenotypes in Stxbp1 -haploinsufficient mice
Abstract Mutations in the syntaxin-binding protein 1 ( STXBP1 ) gene, which encodes the presynaptic protein Munc18-1, cause a spectrum of severe epileptic encephalopathies and neurodevelopmental disorders, including Ohtahara syndrome, for which no curative treatment is currently available. Because the disease pathomechanism is thought to be driven by haploinsufficiency, restoring expression of the wild-type allele to physiological levels could provide therapeutic benefit. Here, we evaluated CRISPR-mediated transcriptional activation (CRISPR-ON), based on a dCas9-VPR transcriptional activator, as a strategy to upregulate endogenous Stxbp1 expression in a Stxbp1 -haploinsufficient ( Stxbp1 +/− ) mouse model. Screening of guide RNAs (gRNAs) targeting the Stxbp1 promoter in Neuro2A cells identified a multiplexed four-gRNA cassette that elevated Stxbp1 mRNA approximately six-fold. AAV-PHP.eB vectors co-expressing this 4xgRNA cassette and Cre recombinase under the EF1a promoter were administered intracerebroventricularly to neonatal Stxbp1 +/− /dCas9-VPR fl/+ mice. CRISPR-ON treatment restored not only brain Stxbp1 mRNA but also Munc18-1 protein levels to those of wild-type controls. Electrocorticographic recordings revealed an approximately 50% reduction in the frequency of spike-wave discharges in CRISPR-ON–treated Stxbp1 +/− mice compared with untreated Stxbp1 +/− controls, and aggressive behavior in the resident-intruder test was also partially attenuated. In contrast, locomotor activity remained unaffected, indicating that CRISPR-ON treatment achieves selective rescue of disease-related phenotypes without inducing motor side effects. Together, these findings demonstrate that CRISPR-ON–mediated activation of endogenous Stxbp1 is a promising therapeutic strategy for STXBP1 -related encephalopathies and support endogenous gene activation as a broadly applicable platform for haploinsufficiency disorders.
2026-02-28 | Cognitive and Motor Dysfunction in STXBP1 R406H Mice.
The STXBP1 protein critically regulates synaptic vesicle fusion and neurotransmitter release, with its mutations implicated in neurodevelopmental disorders. STXBP1 R406H can lead to the occurrence of early-onset epileptic encephalopathy (EOEE). To better elucidate the molecular mechanisms underlying pathogenesis，we generated an STXBP1 R406H mutation mouse model that recapitulated key cognitive-social deficits observed in patients. Behavioral and transcriptomic analyses revealed synaptic impairments and glial activation in mutant mice. Specifically, there is abnormal expression of synaptic proteins in hippocampal neurons, which are correlated with cognitive and motor deficits. Our study establishes that the STXBP1 R406H mutation drives neurodevelopmental pathology via excitatory synaptic dysfunction, offering new mechanistic insights and therapeutic avenues for the treatment of STXBP1-related disorders.
2026-06-29 | Monogenic epilepsies exhibit distinct sleep endophenotypes
Abstract Monogenic epilepsies are 1.6 times more likely to be treatment-resistant compared to other epilepsies, emphasizing the need for additional therapeutic strategies. Sleep dysfunction beyond sleep-related breathing disorders is common yet insufficiently characterized and treated in monogenic epilepsies. We therefore sought to study sleep phenotypes across these epilepsies, examine associations with seizure severity, and assess the diagnostic rate of sleep disorders. From 2,519 individuals enrolled in the Epilepsy Genetics Research Project at Children’s Hospital of Philadelphia, we identified the monogenic epilepsies most frequently associated with sleep-related diagnoses, yielding 252 individuals across nine genetic diagnoses ( STXBP1 , n = 79; SCN1A , n = 57; SCN2A , n = 34; KCNQ2 , n = 21; SLC6A1 , n = 14; SYNGAP1 , n = 13; WDR45 , n = 13; KCNT1 , n = 11; PCDH19 , n = 10). Monogenic epilepsies exhibited distinct sleep endophenotypes, including insomnia, parasomnia, and sleep-related movement disorders in SCN1A -related disorders; frequent epileptiform discharges in sleep with insomnia symptoms in SCN2A -related disorders; sleep dysfunction restricted to the developmental and epileptic encephalopathy subtype in KCNQ2 -related disorders; and insomnia without nocturnal seizure involvement in SYNGAP1 -related disorders. Formal sleep diagnoses were present in only 25% of individuals (63/252), yet 58% (145/252) reported sleep difficulties, suggesting substantial underdiagnosis. Persistent seizures were associated with higher odds of sleep disorder diagnoses ( OR 2.87, 95% CrI 1.57–5.36), disrupted sleep architecture ( OR 2.06, 95% CrI 1.08–4.16), nocturnal seizures ( OR 4.47, 95% CrI 2.50–8.28), hypersomnolence ( OR 2.38, 95% CrI 1.27–4.58) and insomnia ( OR 1.80, 95% CrI 1.06–3.05). Neuropsychiatric comorbidities were independently associated with sleep burden after adjustment for seizure severity ( OR 2.49, 95% CrI 1.40–4.49). We find that monogenic epilepsies exhibit distinct, gene-specific sleep endophenotypes that are underdiagnosed. Treating sleep difficulties beyond obstructive sleep apnoea may improve seizure control and developmental outcomes, highlighting the need for timely diagnosis of co-occurring sleep disorders.
2026-06-09 | CRISPR-mediated Stxbp1 gene activation ameliorates epileptic and aggressive phenotypes in Stxbp1 -haploinsufficient mice
Abstract Mutations in the syntaxin-binding protein 1 ( STXBP1 ) gene, which encodes the presynaptic protein Munc18-1, cause a spectrum of severe epileptic encephalopathies and neurodevelopmental disorders, including Ohtahara syndrome, for which no curative treatment is currently available. Because the disease pathomechanism is thought to be driven by haploinsufficiency, restoring expression of the wild-type allele to physiological levels could provide therapeutic benefit. Here, we evaluated CRISPR-mediated transcriptional activation (CRISPR-ON), based on a dCas9-VPR transcriptional activator, as a strategy to upregulate endogenous Stxbp1 expression in a Stxbp1 -haploinsufficient ( Stxbp1 +/− ) mouse model. Screening of guide RNAs (gRNAs) targeting the Stxbp1 promoter in Neuro2A cells identified a multiplexed four-gRNA cassette that elevated Stxbp1 mRNA approximately six-fold. AAV-PHP.eB vectors co-expressing this 4xgRNA cassette and Cre recombinase under the EF1a promoter were administered intracerebroventricularly to neonatal Stxbp1 +/− /dCas9-VPR fl/+ mice. CRISPR-ON treatment restored not only brain Stxbp1 mRNA but also Munc18-1 protein levels to those of wild-type controls. Electrocorticographic recordings revealed an approximately 50% reduction in the frequency of spike-wave discharges in CRISPR-ON–treated Stxbp1 +/− mice compared with untreated Stxbp1 +/− controls, and aggressive behavior in the resident-intruder test was also partially attenuated. In contrast, locomotor activity remained unaffected, indicating that CRISPR-ON treatment achieves selective rescue of disease-related phenotypes without inducing motor side effects. Together, these findings demonstrate that CRISPR-ON–mediated activation of endogenous Stxbp1 is a promising therapeutic strategy for STXBP1 -related encephalopathies and support endogenous gene activation as a broadly applicable platform for haploinsufficiency disorders.
2026-02-28 | Cognitive and Motor Dysfunction in STXBP1 R406H Mice.
The STXBP1 protein critically regulates synaptic vesicle fusion and neurotransmitter release, with its mutations implicated in neurodevelopmental disorders. STXBP1 R406H can lead to the occurrence of early-onset epileptic encephalopathy (EOEE). To better elucidate the molecular mechanisms underlying pathogenesis，we generated an STXBP1 R406H mutation mouse model that recapitulated key cognitive-social deficits observed in patients. Behavioral and transcriptomic analyses revealed synaptic impairments and glial activation in mutant mice. Specifically, there is abnormal expression of synaptic proteins in hippocampal neurons, which are correlated with cognitive and motor deficits. Our study establishes that the STXBP1 R406H mutation drives neurodevelopmental pathology via excitatory synaptic dysfunction, offering new mechanistic insights and therapeutic avenues for the treatment of STXBP1-related disorders.
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Drug Discovery Landscape
2 orphan drug designations for STXBP1-related encephalopathy.
2 orphan drug designations for STXBP1-related encephalopathy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
recombinant adeno-associated virus capsid enclosing a single-stranded DNA construct encoding human STXBP1 transgene | gene therapies | FDA | 2024-10-19 | — | Capsida Biotherapeutics |
Glycerol phenylbutyrate | small molecules | EMA | 2023-10-13 | — | Immedica Pharma AB |
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