Absence Seizures – Formerly known as petit mal seizures, they are a form of seizure that is described as brief periods of time (roughly 10-20 seconds) where the person stops activity and may appear as if having a vacant stare or daydreaming. Sometimes the eyes may also turn upward or flutter. In rare instances (in atypical absence seizures), a person may also rub their fingers or hand together, eyes may blink, lips may smack or have jerking movements, or make chewing movements with their mouth; are described lasting 5 to 30 seconds. Resource: Epilepsy Foundation (Absence Seizures, symptoms and risks | Epilepsy Foundation) and (Atypical Absence Seizures | Epilepsy Foundation)

Antiepileptic Drugs (AED) – Medications used to treat epilepsy by suppressing seizures. Also known as anticonvulsants. Resource: Epilepsy Foundation (Summary of Antiepileptic Drugs | Epilepsy Foundation)

Antisense oligonucleotides (ASO) – A type of genetic therapy that alters the expression of mRNA in a cell. 

Atonic Seizure – Also known as drop attack or drop seizures, they are a form of seizure where the person loses muscle tone where the head or body will go limp. They typically last less than 15 seconds. Resource: Epilepsy Foundation (Atonic Seizures | Epilepsy Foundation)

Autism – A developmental disorder affecting communication and behavior. It is a disorder which is screened for and diagnosed by a licensed healthcare provider. It is also known as Autism Spectrum Disorder (ASD). Resource: NIMH / NIH


Cerebral Palsy (CP) – A group of neurologic disorders caused by damage or abnormalities in the brain that affect movement, balance, and posture. Resource: NINDS/NIH

Chromosome – A structure in which genetic material is organized. In humans, there are 23 pairs of chromosomes and are designated by numbers 1-22 and the sex chromosomes, X and Y.

Clinical Trials – A type of research study that evaluates a test or treatment in people.


Deletion Mutation – It is a type of mutation that removes genetic material from a gene, including deletion of the entire gene.

Deoxyribonucleic acid (DNA) – It is a basic unit for the storage of genetic information. It includes one of four nucleic acids: adenine (A), cytosine ( C), guanine (G), and thymine (T). The nucleic acids form chemical bonds with specific partners (adenine pairs with thymine; cytosine pairs with guanine) which are known as a “base pair”. DNA includes segments that are used for protein production (or known as coding DNA) and not used for genes (non-coding DNA).  DNA can be transcribed into mRNA (see “mRNA” definition). 

De novo New mutation; disease has not been down from generation to generation.

Duplication Mutation – It is a type of mutation that adds genetic material from a gene.

Electroencephalogram (EEG): A diagnostic test of brain electrical activity.

Electrical status epilepticus of sleep (ESES) – A rare and serious syndrome that is characterized by a particular EEG pattern seen during sleep. It is also known as epileptic encephalopathy with continuous spike and wave during sleep (CSWS). Resource: Epilepsy Foundation (Epileptic Encephalopathy with Continuous Spike and Wave During Sleep (CSWS) | Epilepsy Foundation)

Encephalopathy – A term used to describe a disease of the brain.

Epilepsy – A neurological disorder characterized by recurrent seizures and affects the nervous system.

Epilepsy Panel – A genetic test that analyzes many genes associated with epilepsy with one test.

Exon – Segment of DNA that codes for a gene or part of a gene.

Febrile Seizure – A seizure associated with a high fever in children. Resource: Epilepsy Foundation (Febrile Seizures | Epilepsy Foundation)

Focal Seizures – Also known as partial seizures. Refers to a seizure that starts in one area or network of brain cells on one side of the brain. They can occur with or without loss of consciousness. Some times these seizures are also categorized as: simple (Focal Aware Seizures), complex (Focal Impaired Awareness Seizures), and secondary generalized seizures (Focal to Bilateral Tonic Clonic Seizures). Resources: Epilepsy Foundation (Focal Onset Aware Seizures | Epilepsy Foundation), (Focal Onset Impaired Awareness Seizures | Epilepsy Foundation), and (Focal to Bilateral Tonic-clonic Seizures | Epilepsy Foundation)

Gene – It is a basic unit of heredity and made up of DNA; it can act as genetic instructions to produce proteins. Resource: NIH/Medline Plus – Genetics (What is a gene?: MedlinePlus Genetics)

Genome – A complete set of genetic material of an organism. This includes pairs of 23 chromosomes in the nucleus of a cell and mitochondrial DNA found within the mitochondria of the cell. Resource: NIH/National Genome Research Institute (https://www.genome.gov/genetics-glossary/Genome

Genetic Disorder – A disease that is a result of a change to one or more genes that alters the production of protein that makes it non-functional or missing. Resource: NIH/Medline Plus – Genetics (Genetic Disorders: MedlinePlus)

Gene Variant – It is a mutation in a gene that can change the protein produced which may cause a genetic disorder.


Haploinsufficiency – Chromosomes are arranged in pairs and there are two copies of each gene. For certain genes, both copies are needed to produce a protein. Haploinsufficiency occurs when one of the two genes is non-functional or deleted, and the amount of protein produced is not sufficient for normal functioning.

Hypotonia A condition described as having low muscle tone. Resource: NIH/NINDS (Hypotonia Information Page | National Institute of Neurological Disorders and Stroke (nih.gov))

Incidence – It is a measurement describing the number of events (eg. number of individuals diagnosed with STXBP1) within a defined period of time.

Induced pluripotent stem cells (iPSCs) – Cells collected from the body (ie. skin) that are engineered into being pluripotent (or capable of being changed into other types of cells like neurons) through a specialized laboratory technique. They have been useful in studying biological processes and in drug development.

Infantile Spasms – Also known as West Syndrome. A type of seizure that usually presents with brief episodes of body stiffening and bending forward or backward of the arms, legs, and head (sometimes referred to as “jackknife seizures” or “flexor spasms”). Episodes are brief and often in clusters. Onset usually happens within the first year of life and stops around 4 years of age. Resource: Epilepsy Foundation (Treatment for Infantile Spasms | Epilepsy Foundation)




Lennox-Gastaut Syndrome (LGS) – Resource: Epilepsy Foundation (Case Study on Lennox-Gastaut Syndrome | Epilepsy Foundation)

microRNA: microRNA is the name of a family of molecules that helps cells control the kinds and amounts of proteins they make. That is, cells use microRNA to help control gene expression. Molecules of microRNA are found in cells and in the bloodstream. Resource: Ohio State University

Missense mutation – A type of mutation where a base pair (see “DNA” definition) is changed and it changes what is translated from DNA to mRNA and then final protein.

Myoclonic seizure – Characterized by brief and rapid jerking movements, usually involving both sides of the body at the same time. Resource: Epilepsy Foundation


Neurotransmitter – It is a chemical substance that acts as a messenger between neurons. It is released at one end of a neuron (known as the axon terminal) from synaptic vesicles into a space called the synaptic cleft and received by a receptor of another neuron (known as the dendrite). There are many different types of neurotransmitters and neural pathways that impact functions throughout the body. 

Nonsense mutation – A type of mutation that results in the premature stop codon which results in an incomplete protein. Resource: NIH/NHGRI (https://www.genome.gov/genetics-glossary/Nonsense-Mutation



Phenotype: Phenotype” simply refers to an observable trait Resource: National Human Genome Institute

Precision Medicine – Also known as personalized medicine; it is a concept of tailoring prevention and treatments to an individual to take into account differences in genes, environment and lifestyle. Resource: NIH/Medline Plus – Genetics (What is precision medicine?: MedlinePlus Genetics)

Prevalence – A measurement of the number of people affected (eg. number of people diagnosed with STXBP1) at one particular point in time.




SNARE proteins – In the brain, it is a group of proteins that create a structure known as the “snare complex” that is involved in the release of neurotransmitters into the synaptic cleft.

Sudden Unexpected Death in Someone with Epilepsy (SUDEP) – It is an unexplained death in someone who has epilepsy. It is estimated that more than 1 in 1,000 individuals with epilepsy will die from SUDEP each year and it is the leading cause of death for those with uncontrolled seizures. Resource: Epilepsy Foundation

Synapse – It is the junction of where electrical or chemical signals are transmitted between two neurons. It is made of the presynaptic membrane (where neurotransmitters are released), the synaptic cleft, and the postsynaptic membrane (where neurotransmitters are received).

Syntaxin Binding Protein – 1 (STXBP1) – It is a protein necessary for the release of neurotransmitters


Tonic-Clonic Seizure – Formerly known as Gran Mal seizures. Resource: Epilepsy Foundation (Tonic-Clonic Seizures | Epilepsy Foundation)



Whole Exome Sequencing – A type of genetic testing that identifies the sequences of DNA from regions of the genome that code for proteins.

Whole Genome Sequencing – A type of genetic testing that sequences the entire genome




4-Phenylbutyrate (4PB) – A chemical compound used to treat urea cycle disorders, which is another rare disease unrelated to STXBP1 disorders. Research studies has shown the compound may be useful in treating STXBP1 disorders but it needs to be further evaluated in humans through clinical trials.