What are the signs and symptoms, and how is Duchenne muscular dystrophy diagnose

[Anonymous]

What are the signs and symptoms, and how is Duchenne muscular dystrophy diagnosed?

[Genetic Counselor]

Duchenne muscular dystrophy typically becomes noticeable in early childhood, well before a formal diagnosis is made, since the muscle weakness at first can be subtle and easily mistaken for ordinary clumsiness.
• Motor delay: individuals with DMD are often later than average to walk independently, with an average age of about eighteen months compared to closer to twelve months in unaffected children.
• Gait and mobility: a waddling, proximal pattern of weakness produces persistent toe-walking, a rolling gait, and difficulty running, jumping, climbing stairs, or rising from a squat.
• Gower maneuver: because the muscles around the hips and thighs are especially affected, individuals characteristically use their hands to walk up their own legs when rising from the floor, a distinctive sign doctors look for.
• Calf hypertrophy: the calf muscles often appear enlarged and unusually firm, a finding called pseudohypertrophy, caused by fat and connective tissue replacing muscle fibers rather than true muscle growth.
• Cognitive and behavioral features: dystrophin is also present in the brain, and some individuals with DMD have a degree of intellectual disability, learning disability, attention-deficit/hyperactivity disorder, or autism spectrum features, none of which worsen over time the way the muscle disease does.
• Cardiac involvement: the heart muscle is affected as well, though it usually causes no symptoms in early childhood and becomes more evident in the teenage years.

The average age at diagnosis, when there is no known family history to prompt earlier testing, is around four to five years old. A blood test measuring an enzyme called creatine phosphokinase, or CPK, is usually the first step, since CPK levels are dramatically elevated, generally more than ten times normal, in essentially all individuals with DMD. A markedly elevated CPK level in an individual with the characteristic pattern of weakness is followed by genetic testing of the DMD gene, most often starting with testing designed to detect missing or duplicated exons, since this accounts for the large majority of genetic changes, followed by more detailed sequencing if that initial testing does not identify a cause. A muscle biopsy, once the standard diagnostic tool, is now needed only rarely, mainly when genetic testing is inconclusive.

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