STXBP1 encephalopathy with epilepsy (sometimes called STXBP1 syndrome or STXBP1-related disorder) is a rare genetic condition that affects brain development. It typically causes early-onset epilepsy, developmental delay and intellectual disability, and it is now recognised as one of the more common genetic causes of developmental and epileptic encephalopathy (DEE) in young children. At Rosalind Genetics, we help families across Australia access genetic counselling and genetic testing to find answers, understand results and plan for the future.
What causes STXBP1 encephalopathy with epilepsy?
The STXBP1 gene provides instructions for making a protein called syntaxin-binding protein 1 (also known as Munc18-1). This protein plays an essential role in how brain cells communicate, helping nerve cells release the chemical messengers (neurotransmitters) that pass signals from one cell to the next.
When a pathogenic variant (disease-causing change) occurs in one copy of the STXBP1 gene, the cell does not make enough working protein. This disrupts communication between brain cells and can lead to seizures and differences in development.
In almost all families, the genetic change is de novo, meaning it happened for the first time in the child and was not inherited from either parent. Nothing the parents did before or during pregnancy caused it.
Common signs and symptoms
The features of STXBP1 encephalopathy with epilepsy vary from person to person. Commonly reported features include:
- Seizures beginning in infancy, often in the first few weeks of life. Seizure types can include infantile spasms, tonic seizures, focal seizures and myoclonic jerks
- Developmental delay and intellectual disability, usually moderate to severe
- Speech and language difficulties, with many children having limited or no spoken words
- Low muscle tone (hypotonia)
- Movement differences, such as tremor, unsteady walking (ataxia) or involuntary movements
- Behavioural features, including features that overlap with autism spectrum disorder
A smaller number of people have developmental differences without seizures. Because the condition looks different in each person, care plans should be tailored to the individual child.
Diagnosis and genetic testing
STXBP1 encephalopathy with epilepsy cannot be diagnosed from symptoms alone, as many other conditions cause early-onset seizures and developmental delay. A diagnosis is confirmed through genetic testing, which may include:
- An epilepsy gene panel, which looks at genes known to cause childhood epilepsy
- Whole exome sequencing or whole genome sequencing, which look at thousands of genes at once
- Chromosomal microarray, which can detect larger deletions that include the STXBP1 gene
In Australia, some children with developmental delay or intellectual disability may be eligible for Medicare-funded genomic testing when it is requested by their specialist. Our genetic counsellors can help families understand which testing pathway suits their situation, what results could mean, and what to expect before and after testing.
Management and family support
There is currently no cure for STXBP1 encephalopathy with epilepsy, so care focuses on controlling seizures and supporting development and quality of life. Seizures can be difficult to control, and children often need input from a paediatric neurologist to find the right combination of treatments. Options may include anti-seizure medications, the ketogenic diet and, for some people, vagus nerve stimulation.
Children usually benefit from a multidisciplinary team, which may include paediatricians, neurologists, speech pathologists, occupational therapists, physiotherapists and genetic counsellors. Early access to therapy supports communication, movement and daily living skills, and alternative communication tools can make a real difference for children with limited speech.
Many families also find connection and practical advice through STXBP1 family foundations and broader rare disease support networks.
What does a diagnosis mean for the rest of the family?
Because STXBP1 encephalopathy with epilepsy is usually de novo, the chance of it happening again in a future pregnancy is low. It is not zero, however, because occasionally a parent carries the genetic change in some of their egg or sperm cells without being affected themselves (called germline mosaicism).
Genetic counselling gives families the chance to talk through what this means for them, including options such as testing in a future pregnancy or preimplantation genetic testing (PGT-M) through IVF.
Looking ahead: research and hope
Research into STXBP1 is moving quickly. Scientists are studying how the condition develops and exploring new approaches, including therapies designed to increase the amount of working STXBP1 protein. These treatments are still in the research stage, but each new diagnosis helps clinicians and researchers better understand the condition.
How Rosalind Genetics can help
At Rosalind Genetics, we guide families through every step of their genetic journey, from testing and diagnosis to counselling and ongoing support. If your child has been diagnosed with STXBP1 encephalopathy with epilepsy, or if you are looking for answers about seizures and developmental delay in your family, our compassionate team is here to help.
