Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is a severe, progressive genetic disorder that primarily affects boys and causes muscle weakness and loss of motor function. Symptoms typically appear in early childhood, and most patients experience significant mobility issues by their early teens. Without appropriate care, DMD can affect the heart and respiratory system, reducing life expectancy.

Thanks to recent advances in diagnosis, supportive care, and targeted therapies, the outlook for patients with DMD is gradually improving.

While Duchenne is the most common and severe form of childhood muscular dystrophy, it is part of a larger group of inherited muscle diseases. These include:

• Duchenne Muscular Dystrophy (DMD) – Early onset, rapid progression
• Becker Muscular Dystrophy (BMD) – Later onset, milder and slower progression
• Limb-Girdle Muscular Dystrophies (LGMD) – Affecting shoulder and hip muscles
• Congenital Muscular Dystrophy – Present at birth
• Facioscapulohumeral Muscular Dystrophy (FSHD) – Affecting face, shoulder, upper arms

Duchenne muscular dystrophy (DMD) mainly affects boys and causes progressive muscle weakness that worsens over time.

Symptoms usually start in early childhood and gradually become more severe.

Common signs and symptoms include:

• Delayed motor milestones: such as walking late or difficulty running and jumping
• Frequent falls and trouble getting up from the floor (often using the hands to “climb up” their legs – called Gowers' sign)
• Waddling gait and walking on tiptoes
• Large calf muscles (pseudohypertrophy)
• Fatigue and muscle weakness, especially in the hips, thighs, and shoulders
• Difficulty climbing stairs
• Loss of walking ability: usually occurs by early teens (10–12 years old)
• Scoliosis (curved spine) and joint contractures
• Breathing problems as chest muscles weaken
• Heart problems (cardiomyopathy) as the disease progresses
• Learning difficulties or ADHD symptoms in some children (though intelligence is often normal)

DMD is caused by mutations in the DMD gene, which encodes the protein dystrophin. Dystrophin acts like a shock absorber, protecting muscle cells during contraction.

In DMD patients, the absence or severe reduction of dystrophin leads to repeated muscle damage, inflammation, and progressive replacement of muscle with fat and scar tissue.

The condition is inherited in an X-linked recessive pattern, primarily affecting boys, while female carriers may have mild symptoms.