Understanding Duchenne

Duchenne muscular dystrophy (DMD) is a rare genetic disease that causes muscles to weaken and break down over time. Here’s what families, friends and supporters should know.

What causes it

Duchenne is caused by a change (mutation) in the DMD gene, which carries the instructions for a protein called dystrophin. Dystrophin works like a shock absorber that protects muscle cells as they contract. Without it, muscle fibers are damaged with ordinary use, and over time the body replaces them with scar tissue and fat.

The DMD gene sits on the X chromosome, which is why Duchenne almost always affects boys.
It affects roughly 1 in 3,500 to 5,000 boys born, about 250,000 boys and young men worldwide.
It’s often inherited from a mother who carries the gene change, but about a third of cases come from a brand-new mutation with no family history at all.

How it progresses

Every boy is different, but Duchenne usually follows a general pattern:

Early childhood: signs often appear between ages 2 and 5, such as late walking, frequent falls, trouble with stairs and running, enlarged calves, and using the hands to push up from the floor.
Later childhood and teens: walking becomes harder, and many boys begin using a wheelchair full-time. Weakness spreads to the arms and upper body.
Adulthood: the heart and breathing muscles are increasingly affected, which is why cardiac and respiratory care are central to Duchenne treatment. With modern care, many young men with Duchenne now live into their 30s and beyond.

What it affects

Muscles

Progressive weakness, starting in the hips and legs and moving to the arms and trunk.

Heart

Cardiomyopathy (weakening of the heart muscle) is common, so regular heart monitoring and early treatment are standard.

Breathing

Weaker breathing muscles can mean weaker coughs and breathing support at night, and eventually more.

Bones & more

Scoliosis, bone fragility (made worse by steroids) and joint tightness. Some boys also have learning or attention differences.

How it’s diagnosed

A simple blood test for creatine kinase (CK), an enzyme that leaks from damaged muscle, is often the first clue: CK levels in Duchenne are extremely high. Genetic testing then confirms the diagnosis and identifies the exact mutation, which matters because some treatments only work for specific mutations.

How it’s treated today

There is no cure yet. Care is about slowing the disease, protecting the heart and lungs, and keeping boys as strong and independent as possible, usually through a team of specialists. Treatment options that families discuss with their doctors include:

Corticosteroids, long the backbone of treatment, to help preserve muscle strength.
Newer anti-inflammatory and non-steroid medicines approved in recent years.
Exon-skipping therapies that help the body make a shorter, working dystrophin for certain mutations.
Gene therapy that delivers a shortened “micro-dystrophin” gene, approved for some patients.
Heart and lung care, physical therapy, stretching, braces, and mobility equipment.

Each option has benefits, limits and risks, and which ones make sense depends on the individual. That’s a conversation for a neuromuscular care team.

Learn more

This page is general information, not medical advice. Please talk to a neuromuscular specialist about diagnosis and treatment.