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Glossary of Terms

Clear words for complex topics.

Plain language definitions of the medical and scientific terms you may come across on the Niemann-Pick disease journey.

Making Sense of Medical Terms

A Niemann-Pick disease diagnosis comes with a whole new vocabulary.

Niemann-Pick disease is a group of rare, inherited conditions that affect how the body’s cells process and store fats such as cholesterol and sphingomyelin. Its main forms, acid sphingomyelinase deficiency (ASMD, once known as types A and B) and Niemann-Pick type C (NPC), can affect the liver, spleen, lungs and brain.

Doctor visits, test results, research updates and clinical trial materials are often full of unfamiliar words. The National Niemann-Pick Disease Foundation put together this glossary of more than 140 terms, each explained in plain language, so patients, families, caregivers and friends can follow the conversation, ask informed questions and feel more confident about the next step.

Search the Glossary

A comprehensive glossary of NPC and ASMD terms. Search for a word, or choose a letter to browse.

2-hydroxypropyl-β-cyclodextrin
A specific type of cyclodextrin molecule used experimentally in NPC treatment; also known as HP-β-CD, helps remove trapped cholesterol from cells. Two forms used in clinical trials in NPC are Trappsol Cyclo and Adrabetadex
Acid Sphingomyelinase Deficiency (ASMD)
A rare genetic disorder caused by deficiency of the enzyme acid sphingomyelinase, leading to accumulation of sphingomyelin in cells. This name is now used to represent the spectrum disorder previously known as Niemann Pick type A and Niemann Pick type B.
Adrabetadex
Name for a specific HP-β-CD (2-hydroxypropyl-β-cyclodextrin) currently being studied and under development for NPC
Aqneursa
Brand name for levacetylleucine approved by the FDA to treat the neurological symptoms in NPC
Arimoclomol
Generic name for Miplyffa
Ataxia
Loss of coordination and balance; a common neurological symptom that affects walking, speech, and fine motor skills
Autosomal Recessive
A pattern of genetic inheritance where a person must inherit two copies of a defective gene (one from each parent) to develop the condition; this is how NPC and ASMD are inherited
Azafaros
A biopharmaceutical company developing nizubaglustat.
Biologic
A type of drug made from living organisms or their cellular components such as altered proteins, antibodies, genes or DNA; different from traditional chemical drugs. Xenpozyme (olipudase alfa) is an example of a biologic
Biological Activity
Measurable effects that a drug has on the body’s biological processes
Biomarker
Biomarkers serve as objective signs that can be detected and measured outside of the patient’s subjective experience. A biomarker can be a measurable biological indicator found in blood, other body fluids, or tissues that can signal normal biological processes, disease states, or responses to treatment. Other examples of biomarkers include MRIs and data obtained from digital health technology
Body Surface Area (BSA)
A measurement used to calculate appropriate drug doses, especially in pediatric patients
Capsules
The oral dosage form for medications like Miplyffa and miglustat
Carrier
A person who has one copy of a gene mutation for an autosomal recessive condition like NPC; carriers typically don’t have symptoms but can pass the mutation to their children
Case-Control study
A type of observational study that compares people with a disease (cases) to people without the disease (controls) to identify factors that may contribute to the condition
Cataplexy
Sudden loss of muscle tone triggered by strong emotions; a neurologic symptom that can occur in some NPC patients
Cell (Plasma) Membrane
The outer boundary of cells that controls what enters and exits; can be affected by the abnormal cholesterol accumulation in NPC
Cell Trafficking
The process by which cells transport materials and organelles within themselves and between different cellular compartments; disrupted in NPC due to cholesterol accumulation
Cellular Activity
The various processes that occur within cells, including energy production and signaling
Ceramide Glucosyltransferase
An enzyme involved in producing glycosphingolipids; targeted by some NPC treatments
Cerebrospinal Fluid (spinal fluid)
The fluid that surrounds the brain and spinal cord; can be sampled to assess the state of the disease and is being used as a delivery route for some NPC treatments under development
Cherry Red Spot
A characteristic finding in the eye examination where the macula appears as a red spot surrounded by a pale area; this finding is present in some ASMD patients and as well as patients with other lysosomal storage diseases
Cholesterol metabolism
The body’s process of producing, using, and breaking down cholesterol
Clinical Trial
A research study that tests new treatments in people to determine safety and effectiveness
Coagulation Studies
Blood tests that measure how well blood clots; important to monitor in patients with liver disease or those taking certain medications
Cognitive Impairment
Problems with thinking, memory, and mental processing
Cohort
A group of people followed over time in a research study to observe outcomes and disease progression; can be prospective (following forward in time) or retrospective (looking back at past data)
Combination Therapy
Using two or more medications together
Compassionate Use
A treatment option that allows the use of an unauthorized medicine. Under strict conditions, products in development can be made available to groups of patients who have a disease with no satisfactory authorized therapies and who cannot enter clinical trials
Creatinine
A kidney-related blood test marker that may increase with some NPC medications
Cyclo Therapeutics
A biopharmaceutical company developing Trappsol Cyclo, a type of cyclodextrin. Cyclo Therapeutics is a subsidiary of Rafael Holdings.
Cyclodextrin
A type of molecule under study that can help remove trapped cholesterol and other fatty substances from cells
Demyelination
The loss or damage of myelin, the protective covering around nerve fibers; can occur in NPC and contributes to neurological symptoms
Dexel Pharma
Manufacturer of Yargesa (miglustat)
Digital Health Technology
The use of information and communications in medicine and other health professions to manage illnesses and health risks and to promote wellness.
Disease Progression
How a condition like NPC worsens or advances over time
Dosing Schedule
The specific timing and frequency for taking medications
Double-Blind
A clinical trial design where neither the participants nor the researchers know who is receiving the active treatment versus placebo, helping to eliminate bias in results
Drug Interactions
When one medication affects how another medication works in the body
Drug Repurposing
The process of discovering and developing new therapeutic uses for existing drugs that have already been approved for a different condition. An example is the investigation of efavirenz for use in NPC
Dual Inhibitor
A drug that blocks two different enzymes or pathways simultaneously
Dysphagia
Difficulty swallowing; a common symptom in NPC that can affect eating, drinking, and taking medications
Efavirenz
A medication approved by the FDA to treat HIV that is being studied as a potential treatment for NPC
End Point (clinical trial endpoint)
The main goal or the specific thing the researchers are looking for to decide if the treatment was successful. It’s a measurable outcome that tells them if something changed because of the treatment.
Energy Metabolism
How cells produce and use energy
Enzyme replacement therapy (ERT)
A treatment approach used for certain genetic disorders where the body lacks or produces insufficient amounts of specific enzymes needed for normal cellular function. Xenpozyme (olipudase alfa) is an enzyme replacement therapy for ASMD.
European Medicines Agency (EMA)
The regulatory body that approves medications in Europe
Expanded Access Program (EAP)
The formal plan under which access to an investigational drug can be provided to a group of patients prior to being approved by the FDA outside of a clinical trial.
Extension Study
A subsequent, usually longer, clinical trial that allows participants from a “parent” clinical trial to continue receiving the same treatment to gather more long-term safety, tolerability, and effectiveness data
FDA (Food and Drug Administration)
The U.S. regulatory body that approves medications
Feeding Tube (G-tube)
A medical device that allows medication delivery directly to the stomach
Fetal Harm
Potential damage to an unborn baby from certain medications
Gaucher Disease
Another lysosomal storage disorder that has features similar to ASMD; miglustat is approved for this condition in the U.S.
Gene Therapy
An experimental treatment approach that involves introducing genetic material into cells to correct defective genes or provide new cellular functions
Glycosphingolipids
Fatty substances that accumulate abnormally in some lysosomal diseases
Granules
The powder form of AQNEURSA that must be mixed with liquid
Heat Shock Proteins (HSPs)
Natural protective proteins that help cells survive stress and repair damage
Hepatic Function Panel
A group of blood tests that assess liver function, including tests for liver enzymes, bilirubin, and protein levels; important for monitoring patients with ASMD and NPC
Hepatosplenomegaly
Enlargement of both the liver and spleen; can occur in both ASMD and NPC
Hives (Urticaria)
A skin reaction that can occur as an allergic response to medications
HP-β-CD (2-hydroxypropyl-β-cyclodextrin)
A specific type of cyclodextrin under study for the potential treatment of NPC
Hypersensitivity Reactions
Allergic reactions that can range from mild to severe
Industry
The pharmaceutical and biotechnology companies that research, develop, manufacture, and market new medicines
Insurance Appeal
Formal process to challenge a health insurance company’s decision to deny a claim, service, or benefit you believe should be covered. It involves two main steps: an internal appeal, where the insurer reviews its own denial, and an external appeal, where an independent third party makes the final decision if the internal appeal is unsuccessful. You have the right to appeal when your plan denies payment for treatment, coverage, or a service.
IntraBio
A biopharmaceutical company that is the manufacturer of Aqneursa (levacetylleucine)
Intrathecal
Method of drug delivery directly into the cerebrospinal fluid around the brain and spinal cord
Intravenous (IV)
Method of drug delivery directly into the bloodstream through a vein
Johnson & Johnson
Manufacturer of Zavesca (miglustat)
Large Molecule
A complex biological agent (like a protein and antibody) produced in living systems and generally requiring injection to be administered.
Levacetylleucine
Generic name for Aqneursa; also called by its chemical name N-acetyl-L-leucine
Liver Tests
Blood tests that check liver function; may change with some NPC medications
Lumbar Puncture
A procedure (spinal tap) used to deliver medication directly into the cerebrospinal fluid
Lysosomal Storage Disorder (LSD)
A group of genetic diseases, including ASMD and NPC, where substances accumulate in cellular compartments called lysosomes
Lysosome
Cellular compartments that normally break down and recycle cellular waste; dysfunction of lysosomes is central to ASMD and NPC pathology
Managed Access Program
Allows patients to receive a medicine that is not yet fully approved or available in their country, typically for serious conditions when no other treatment options exist. These programs ensure that access is controlled and monitored, often under specific compassionate use or expanded access regulations
Mandos Health
A biopharmaceutical company developing adrabetadex, a type of cyclodextrin. Mandos is a subsidiary of Beren Therapeutics
Mandose
A sugar molecule that can be used as a biomarker or therapeutic target in some lysosomal storage disorders; involved in cellular recognition and trafficking processes
Medicaid
A joint federal and state public health insurance program that provides low-cost health coverage to low-income individuals, families, pregnant women, elderly adults, and people with disabilities. Administered at the state level but funded jointly by federal and state governments, Medicaid offers a wide range of medical services, including hospital care, doctor visits, and long-term care, with eligibility and covered benefits varying by state.
Medicaid Waiver
A formal agreement between a state and the federal government that allows the state to test new ways to deliver Medicaid services or provide coverage for people who might not normally be eligible. The most common waivers, Section 1915(c) Home and Community-Based Services (HCBS) waivers, enable states to offer long-term care services in a person’s home or community, rather than in an institution, by providing services like personal care, respite care, and home modifications.
Medicare
A federal health insurance program in the U.S. primarily for people aged 65 or older, but also for certain younger people with disabilities or End-Stage Renal Disease (ESRD). It helps pay for healthcare costs, broken down into different parts (A, B, C, and D) that cover hospital stays, doctor services, outpatient care, and prescription drugs.
Miglustat
A drug with a complex mechanism of action in treating Gaucher disease (FDA approved) and NPC (off-label use) that includes reducing the production of glycosphingolipids through a process known as substrate reduction therapy; brand names include Zavesca and Yargesa
Miplyffa
Brand name for arimoclomol; approved by the FDA for use in combination with miglustat for the treatment of neurological symptoms of NPC
Monotherapy
Treatment with a single medication rather than combination therapy
Movement Disorders
Problems with coordination, balance, and motor control that can occur in ASMD and NPC
N-acetyl-L-leucine
Chemical name for levacetylleucine (Aqneursa)
NDA (New Drug Application)
The formal application submitted to the FDA requesting approval to market a new drug in the United States
Neurological Decline
The progressive worsening of brain-related symptoms
Neurological Progression
The worsening of brain-related symptoms over time
Newborn Screening
Testing performed on newborn babies to identify genetic disorders and other conditions early in life; some forms of Niemann-Pick disease can be detected through newborn screening programs
Niemann-Pick Disease Type C (NPC)
A rare genetic disorder where cholesterol and other fatty substances accumulate in cells, causing progressive neurological damage
Nizubaglustat
An investigational drug that acts as a dual inhibitor to reduce cholesterol in cells via substrate reduction, meaning it blocks two different enzymes involved in the body’s processing of certain lipids, or fats currently under development for the treatment of NPC
Non-lysosomal Glucosylceramidase
An enzyme involved in breaking down certain fatty substances; targeted by some treatments
NPC-CSS (Niemann-Pick Type C Clinical Severity Scale)
A standardized tool used by clinicians to quantify the severity and progression of Niemann-Pick type C disease. It assesses various symptoms, providing a numerical score that helps track disease course and evaluate the impact of therapies over time.
Observational Study
A type of research study where investigators observe participants without intervening or assigning treatments; includes cohort studies, case-control studies, and cross-sectional studies
Off-Label
The practice of prescribing an FDA-approved medication for a condition, age group, or dosage different from what it was originally approved for; this type of prescribing is legal and common in medical practice
Oligosaccharide
A type of molecule made of multiple sugars linked together. These molecules can serve many functions that impact cell function and cell communication.
Olipudase alfa
Generic name for Xenpozyme
Open-label Study
A clinical trial where both patients and doctors know what treatment is being given
Oral Administration
Taking medication by mouth
Organomegaly
Enlargement of organs, particularly the liver, spleen, or other internal organs; commonly seen in lysosomal storage disorders like ASMD and NPC
Patient Reported Outcome (PRO)
Measurements of health status, symptoms, or quality of life reported directly by patients rather than healthcare providers
Peripheral Neuropathy
Nerve damage that can cause numbness, tingling, or weakness, especially in hands and feet
Petechiae
Small, pinpoint red or purple spots on the skin caused by minor bleeding from broken capillary blood vessels; can indicate low platelet count or bleeding disorders
Pharmacodynamics
The study of what a drug does to the body
Pharmacokinetics
The study of what the body does to a drug (how it is absorbed, distributed, metabolized, and eliminated)
Pharmacy Benefits Manager (PBM)
A third-party administrator that manages prescription drug benefits on behalf of health insurance companies, large employers, and other payers. PBMs negotiate drug prices with pharmaceutical manufacturers, create formularies (lists of covered drugs), manage pharmacy networks, and process prescription claims. They act as intermediaries between health insurance plans, pharmacies, and drug manufacturers.
Phase I Trial
A small trial involving healthy volunteers that is designed to determine the safety and tolerability of a drug.
Phase II Trial
A study involving people with a specific disease to determine efficacy while still monitoring for safety as is done in a phase I study.
Phase III Trial
Often referred to as a confirmatory trial, this study determines efficacy of an intervention or drug compared to the standard of care at that time. These trials are typically larger than phase I or II trials.
Phase IV Trial
A study done after a drug is approved and available designed to assess a therapy’s long-term risks, benefits and optimal use.
Placebo
An inactive treatment used as a control in clinical trials to compare against the actual medication being tested
Plain Language Summary
A simplified version of detailed scientific or medical article.
Prescribing Information
Also known as “the label,” the official documentation that provides detailed information about how to use a medication safely
Prior Authorization
A process requiring a prescriber to get approval from an insurance company before they reimburse for a specific medication or treatment
Protein Folding
The process by which proteins achieve their proper shape and function; enhanced by heat shock proteins
Randomized
A study design where participants are assigned to treatment groups by chance rather than by choice, helping to eliminate bias in clinical trials
Randomized Controlled Trial (RCT)
The gold standard study design where patients are randomly assigned to either the treatment or control groups
Registry
A systematic collection of data about patients with a particular condition, used to track disease progression and treatment outcomes over time
Regulators
Government agencies or bodies responsible for overseeing and approving new medicines before they can be sold to the public. Their main job is to make sure that any new drug is both safe for patients to use and effective for the condition it’s meant to treat.
Retail Pharmacy
A licensed establishment that dispenses prescription and over-the-counter medications directly to the public at retail prices, typically in a community setting.
Retrospective Study
A research study that looks backward in time, examining data that has already been collected to identify patterns or outcomes.
Sachets
Single-use packets containing Aqneursa granules.
Sanofi
A biopharmaceutical company that is the manufacturer of Xenpozyme (olipudase alfa).
Seizures
A sudden, abnormal burst of electrical activity in the brain that can cause temporary changes in behavior, movement, consciousness, or sensation.
Sensitivity
In medical testing, the ability of a test to correctly identify people who have a disease (true positive rate); important for diagnostic tests and screening programs.
Side Effects
Unwanted effects that can occur when taking medications.
Single-Blind
A clinical trial design where either the participants or the researchers (but not both) know who is receiving the active treatment versus placebo
Small Molecule
A low-molecular-weight (small) compound with a simple structure that is often made chemically (as opposed to being made in a living system), allowing it to easily enter cells and cross the blood-brain barrier. These are often administered orally.
Spasticity
Muscle stiffness and involuntary contractions that can occur due to damage to the brain and spinal cord pathways that control movement
Specificity
In medical testing, the ability of a test to correctly identify people who do not have a disease (true negative rate); important for avoiding false positive results
Step Therapy (aka step protocol)
A health plan program that requires patients to try a more cost-effective, often generic, medication for a condition before covering a more expensive, less cost-effective one.
Substrate Reduction Therapy
Treatment approach that reduces production of harmful substances rather than trying to break them down; the mechanism of action for miglustat and nizubaglustat
Summary of Product Characteristics (SmPC)
European equivalent of prescribing information
Supranuclear Gaze Palsy
A characteristic eye movement disorder in NPC where patients have difficulty moving their eyes up and down voluntarily
Thrombocytopenia
A condition characterized by abnormally low platelet count in the blood, which can lead to increased bleeding and bruising; may occur in some lysosomal storage disorders like ASMD and NPC
Transaminase
Liver enzymes (including ALT and AST) that are measured in blood tests to assess liver function; levels may be elevated in patients with liver involvement from ASMD and NPC or as a side effect of medications
Transcription
The cellular process of copying genetic information from DNA to RNA
Trappsol Cyclo
Proprietary name for a specific HP-β-CD (2-hydroxypropyl-β-cyclodextrin) currently under study and development for NPC
Tremor
Shaking or trembling that can occur in NPC or as a medication side effect
Upper Respiratory Infections
Common cold-like symptoms that can occur as medication side effects
White Matter Disease
Damage to the white matter of the brain, which contains nerve fibers that connect different brain regions. These findings are commonly seen on MRIs
Xenpozyme
Brand name for olipudase alfa, an enzyme replacement therapy approved by the FDA used to treat the non-neurologic symptoms in ASMD
Yargesa
Brand name for miglustat manufactured by Dexel Pharma approved by the FDA for the treatment of Gaucher disease
Zavesca
Brand name for miglustat manufactured by Johnson & Johnson approved by the FDA for the treatment of Gaucher disease
Zevra Therapeutics
A biopharmaceutical company that is the manufacturer of Miplyffa (arimoclomol)

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