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Amino acid: a type of compound that is the building block of proteins.


Byproduct: a substance that is created in the process of making something else.


Caregiver: someone who regularly looks after and provides care or assistance to someone, such as a child, an elderly person, or someone who is sick or disabled.

Cerebral palsy: a disability resulting from damage to the brain before, during, or shortly after birth that causes issues with body movement, muscle tone, speech disturbances, and/or other medical issues.

Cerebrospinal fluid (CSF): the fluid surrounding the brain and spinal cord.

Clinical Geneticist: a physician who is trained to help identify and study genetic disorders.

Computed tomography (CT): a scan that uses a series of X-ray images taken from different angles around the body and uses computer processing to create a cross-sectional image of the inside of the body.


Deficiency: a lack or shortage of something.

DDC (dopa decarboxylase) gene: a gene that provides instructions for making the enzyme aromatic L-amino acid decarboxylase (AADC), which is important in the brain and nervous system.


Electroencephalography (EEG): a test that looks at abnormalities in the brain by attaching small metal electrodes to the scalp in order to detect tiny electrical charges from brain activity.

Enzyme: a substance that helps to bring about, speed up, or regulate chemical reactions.

Epilepsy: a chronic disorder that causes sudden episodes in which the patient may lose consciousness, have his/her senses disrupted, shake uncontrollably, and/or show other symptoms (for example, seizures or fits); often caused by abnormal electrical activity in the brain.


Flailing: waving or swinging wildly.


Gastroenterologist: a medical professional who specializes in identifying and treating disorders of the stomach and intestines.

General Practitioner: a medical professional who is trained to provide health care to patients of any gender or age.

Genetic: relating to or determined by genes; something that is passed down through families and considered inherited.

Genetic testing: a study of DNA to find differences, abnormalities, or changes that could cause disorders or to determine if a person has or will develop a certain disease.


Hypotonia: low muscle tone, often involving reduced muscle strength.


Involuntary: done without conscious control.


Lumbar puncture: a medical procedure in which fluid from the spine is removed with a needle; often done for diagnostic testing. Also called a spinal tap.


Magnetic resonance imaging (MRI): a test that uses a magnetic field and radio waves to create detailed images of the body’s organs and structures.

Metabolite: any substance that is made during the changing of one chemical compound into another.

Movement Disorder Specialist: a healthcare professional who has special training in disorders that affect someone’s ability to move, such as Parkinson’s disease, or that involve low muscle tone (hypotonia) or tremors.

Muscle spasm: an uncontrolled tightening of a muscle that can cause a great deal of pain.

Muscle tone: the amount of tension or resistance in a muscle at rest or in response to stretching.

Mutation: a change that happens in a gene.


Nervous system: an organ system of the body made up of the brain, spinal cord, and nerves.

Neurological: relating to the makeup, functions, and disorders of the nervous system.

Neuromuscular: relating to nerves and muscles.

Neurotransmitter: a chemical substance that works as a messenger to send signals from one nerve cell to another.


Occupational Therapist: a healthcare professional who works to help mentally, physically, and developmentally disabled patients improve their ability to participate in everyday activities.

Oculogyric crises: periods of involuntary eye movements during which the eyes suddenly roll upward involuntarily; can last anywhere from a few seconds to hours, and can happen several times a day or several times a week.


Pediatrician: a medical professional who specializes in the development, care, and treatment of children and their diseases.

Pediatric Neurologist: a medical professional who focuses on studying and treating diseases and conditions that affect the nervous system of children.

Physical Therapist: a trained healthcare professional who helps patients reduce pain and strengthen muscles to improve mobility.

Plasma: the colorless fluid part of blood.

Precursor: a substance from which another substance is created.


Reflux: to flow backward in the body, such as from the stomach.


Seizure: a sudden attack, spasm, or convulsion, as in epilepsy or another disorder.

Speech Therapist: a healthcare professional who specializes in the treatment of speech and communication disorders.

Symptom: an indication of a disease or a change in a condition that the patient notices.

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