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12 | InTouch AUTUMN 2025 Duchenne muscular dystrophy (DMD) is a progressive muscle disease that affects approximately 1 out of every 3500 to 5000 baby boys born. Duchenne muscular dystrophy (DMD) YOUR CONDITION IN REVIEW Duchenne muscular dystrophy (DMD) is the most common of the muscular dystrophy disorders and is caused by an absence or marked deficiency of a protein called dystrophin. Closely related to DMD is Becker muscular dystrophy (BMD) which is caused by a decreased or abnormal quality of the same dystrophin protein is named after the French neurologist Guillaume Benjamin Amand Duchenne (1806–1875), who described and detailed the case of a boy who had this condition in a book published in 1861. Features of DMD The symptoms usually appear before age 6 and may appear as early as infancy. Typically, the first noticeable symptom is delay of motor milestones, including sitting and standing independently. The mean age for walking in boys with DMD is 18 months. There is progressive muscle weakness of the legs and pelvic muscles, which is associated with a loss of muscle mass (wasting). This muscle weakness causes a waddling gait and difficulty climbing stairs. Getting up off the floor is difficult and boys tend to use their arms to support the torso when doing this (called the Gower Manoeuvre). Muscle weakness also occurs in the arms, neck, and other areas, but not as severely or as early as in the lower half of the body. Enlarged calf muscles may be noticed at a young age. This enlargement is called pseudohypertrophy, or “false enlargement,” and is due to damaged muscle tissue being replaced with fat and connective tissue. Muscle contractures (permanent shortenings) can occur in the legs resulting in impaired range of motion and toe walking. There is a steady decline in muscle strength between the ages of 6 and 11 years. By age 10, braces may be required for walking, and by age 12, most boys require a wheelchair. Bones are also affected and may not develop Above: In people with DMD, glycogen cannot be broken down and builds to toxic levels inside cells.