CALEB, living with Duchenne,
and his family.

Duchenne Dictionary



6-Minute Walk Test (6MWT)

A test that has been used in clinical trials to determine how far a person can walk in 6 minutes on a hard, flat surface, which helps doctors measure strength and endurance. It is typically measured in meters.

Accelerated approval

An FDA regulation that allows early approval for drugs that treat serious conditions or address an unmet medical need. Approval may be granted based on a surrogate endpoint—a measure that reasonably predicts how well a drug may work. Additional clinical trials may be required, and if the drug does not work, the FDA can withdraw approval.


Drugs, like steroids, that help reduce inflammation—or swelling—in the muscles.


Part of the immune system that helps recognize foreign substances (like bacteria and viruses) and helps get rid of them. There are many types of antibodies, and each specific to a different foreign substance that the body has been exposed to before.

Attention-deficit/hyperactivity disorder (ADHD)

A common childhood disorder that includes symptoms such as difficulty staying focused and paying attention, difficulty controlling behavior, and hyperactivity (over-activity).

Autism spectrum disorders (ASD)

A wide range of symptoms or impairments often associated with autism. These include frequent challenges in interacting with others, and restricted, repetitive patterns of behavior, interests, or activities. Symptoms must be present early in life (typically in the first two years), and they must cause clinically significant impairment in social, occupational, or other important areas of functioning.


Becker muscular dystrophy

An inherited disorder that involves slowly worsening muscle weakness of the legs and pelvis. It is very similar to Duchenne muscular dystrophy, except that it is a milder form.


Short for biological markers, they are used in research and clinical practice to measure normal biological processes, disease-causing processes, or the body's response to medicines. For example, blood sugar levels are a kind of biomarker that can be used in clinical trials to see if a new, experimental diabetes medication is working.


A procedure that removes cells or tissues from the body so doctors and researchers can examine them more closely.

Breakthrough therapy

A type of drug that can be developed and reviewed faster by the FDA if evidence from early clinical trials shows that it is a substantial improvement compared with other available treatments. The evidence can include the effect of the drug on serious symptoms, or how it provides life-saving benefits.


Carrier testing

A type of genetic testing that is used to see whether a person has a specific genetic mutation, or error, that could cause a specific disease in his/her children. This kind of testing is used most often by couples who are considering becoming pregnant to determine the risks of their child inheriting one of these genetic disorders.

Clinical drug trial

A type of research study that provides evidence of a new drug's safety and efficacy, or how well it works. Clinical trials may also compare a new treatment with a treatment that is already available. More generally, clinical trials can also involve testing not only drugs, but also devices and other interventions, such as diet or exercise.

Clinical endpoint

A measurement used in clinical trials; generally the most reliable way to measure response in clinical trials. They directly measure the ability to feel better, function better, or live longer.


Medications that are the most commonly used for Duchenne. A doctor may prescribe these drugs to help slow down the muscle damage and weakness caused by the disease. They work by reducing inflammation — or swelling — in the muscles. They may also help the heart and lungs remain stronger longer, and reduce the chance of having a severely curved spine (a condition called scoliosis). There are various types of steroids; corticosteroids are just an example.

Creatine kinase

Also known as CK, creatine kinase (kree-uh-teen kine-ace) is an enzyme that muscle cells need to function.

Creatine kinase test

Also called a CK test, a test that measures how much CK is in your blood. CK typically leaks out of damaged muscle cells, and this test can help doctors tell whether muscle damage is present. This test is often the first step to see if genetic testing is needed.



A type of error in your genes where genetic material is missing. It can be small, like a single rung on the DNA ladder, or large, involving large sections of DNA.

Disease progression

How a disease impacts a person over time.


Short for deoxyribonucleic acid (dee-oxy-rybo-new-clay-ick acid), DNA carries all our genetic information. It is found in nearly every cell in our body.


A type of error in your genes where there are extra copies of a part of a gene, a whole gene, or a series of genes.


A protein muscles need to work properly. It helps strengthen and protect the cells in our muscles as we use them. When you don't have enough or any dystrophin, muscles can become damaged and weak.

Dystrophin gene

The dystrophin gene, also called the DMD gene, it is the largest gene in the body. The mRNA that comes from the dystrophin gene contains 79 exons that are linked together to form the instructions for making dystrophin, a protein muscles need to work properly.



A section of DNA or RNA that helps provide the instructions for making proteins.

Exon skipping

A potential treatment that researchers are exploring for Duchenne muscular dystrophy. Many people with Duchenne have a genetic mutation in which one or more exons (a section of a gene) in the dystrophin gene are missing. This causes errors in the instructions for making dystrophin, leaving the body unable to produce a working form of the protein. Exon skipping is a technology that tells the body to hide an exon next to the missing piece, so the whole section can be skipped over and the rest of the exons can fit together.


Please see "protein expression."

External control group

A group of people with similar characteristics to individuals in a clinical trial but who are not on treatment. Their results are compared to see if the potential treatment is making a difference.


Fast track

A process designed to help shorten the time it takes to develop and review drugs that treat serious conditions and fill an unmet medical need. It allows early and frequent communication between the drug company and the FDA to help resolve questions and issues quickly.


Short for the US Food and Drug Administration, the FDA is a government agency responsible for safeguarding public health by assuring that current and new medical products are safe and effective, and that the evaluation of potential new therapies is done properly. They are here to protect and promote your health, and protect your rights as a participant in clinical trials.


Similar to scarring, it is a thickening of connective tissue. In Duchenne, it causes muscle fibers to be replaced by fat and connective tissue, which prevents muscles from working properly.



A gene is a section of DNA that helps provide the instructions for making a protein.

Genetic condition

A disease caused by a change in our genes. Some changes are inherited or passed down from parents, while others happen randomly.

Genetic counselor

A healthcare professional who is trained in medical genetics and counseling.

Genetic mutation

A permanent change in a person’s DNA. Mutations can range in type and size, and each mutation could cause a different effect on our bodies. Some mutations may not impact the body noticeably or at all.

Genetic test

A form of laboratory testing (typically a blood or saliva test) that can detect genetic mutations and help confirm or rule out whether a person has a genetic disease. It may also help people understand the risk of passing on a mutation to their children.


An individual's collection of genes.

Gower's maneuver

A series of movements that young children with Duchenne use to support themselves when trying to stand up. They use their hands to "walk" up their legs when trying to stand up.



A test that takes a picture of a cell to see if a protein is present and, if so, where it’s located within the cell.


A type of test used in clinical trials to show if there is dystrophin and where it is located in muscle tissue. A muscle biopsy is required to conduct this test.

Informed consent

A part of the clinical trial process that helps you and your child decide whether to be part of a particular clinical trial. Eligible children and their families are given the key facts about the study before it starts, including the risks and benefits of participation.


Muscle biopsy

Please see “biopsy.” 


Natural history

The normal progression of a disease. It allows us to better understand what happens to a person with the disease if no treatments are used or if certain treatments are used.


A type of brain cell that transmits nerve impulses.


Also called the North Star Ambulatory Assessment, it is a test that evaluates a patient's ability to perform 17 everyday activities, such as standing, walking, rising from the floor, hopping, jumping, climbing, and running.


Obsessive-compulsive disorder (OCD) 

A pattern of unreasonable thoughts and fears (obsessions) that lead you to do repetitive behaviors (compulsions). These obsessions and compulsions interfere with daily activities and cause significant problems.



A pill or liquid with no active ingredients. These are used in clinical trials to test whether trial medications are effective.

Point mutation

A type of error in our genes, in which a single rung on the DNA ladder is missing or altered.

Priority review

A process that means the FDA will aim to take action on a new drug application within 6 months (compared with 10 months under standard review).

Progressive disease

A disease or physical ailment that gets worse or spreads over time. This may happen until death, serious physical weakness, or organ failure occurs.


One of the 3 key parts in gene therapy (along with the vector and transgene). Its goal is to "turn on" the transgene once it’s in the correct cells. There are many different types of promoters that can be considered for a gene therapy.

Protein expression

How proteins are made.


The building blocks for almost all the tissues in the body. They are essential for our bodies to function. Each protein has a special job. For example, the dystrophin protein is needed for muscles to work properly.


The action plan of a clinical trial, it describes in detail how the research will be done, including who can participate, how long the study will run, which tests, procedures, medicines and doses will be used, and what information will be collected. Protocols are reviewed and approved by a group of experts, called an Institutional Review Board (IRB), which includes doctors, researchers, and community members.

PUL (Performance of Upper Limb)

A test used to see how well someone with Duchenne can use their shoulders, arms, wrists and hands.



Short for ribonucleic acid (rye-boh-new-clay-ick acid), RNA is a single-stranded working copy of the DNA instructions that cells use to build proteins.


Spontaneous mutation

A genetic mutation that occurs in the absence of a family history for the disorder.

Surrogate endpoint

Biomarkers that are used instead of clinical endpoints in some clinical trials. A biomarker is a physical, biochemical or genetic characteristic that can be objectively measured.



One of the 3 key parts in gene therapy (along with the vector and promoter), the transgene is the new gene that is delivered to cells. Its goal is to provide the instructions cells need to make the new protein. Each gene therapy uses a different transgene, even when its designed to treat the same disease.



A protein in muscle cells that resembles dystrophin and performs a very similar function. It is produced in the early stages of muscle development, but is then “turned off” in favor of dystrophin.



One of the 3 key parts in gene therapy (along with the promoter and transgene), the vector is designed to carry the transgene and promoter to the target cells. There are many different types of vectors that can be considered for a gene therapy. Which one researchers choose can impact how well a gene therapy works and what potential side effects someone may have.


Western blot

A test used in clinical trials to show if a specific protein (like dystrophin) is present in muscle cells and, if so, how much of the protein is there. A muscle biopsy is required to collect the cells needed for the test.

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