Muscular dystrophy

Causes and inheritance

All forms of muscular dystrophy arise from mutations in genes important for muscle structure or function. These mutations can disrupt proteins that stabilize muscle fibers, causing repeated damage and gradual replacement of muscle with fat and connective tissue. Inheritance patterns include X-linked, autosomal dominant and autosomal recessive transmission. For example, the absence of functional dystrophin — a structural protein — causes the severe X-linked Duchenne muscular dystrophy.

Major types

• Duchenne muscular dystrophy: typically appears in early childhood and mainly affects boys; progressive and often severe.
• Becker muscular dystrophy: similar to Duchenne but generally milder and with later onset.
• Myotonic dystrophy: notable for prolonged muscle contractions and multisystem effects including cataracts and endocrine changes.
• Facioscapulohumeral, limb-girdle and other regional forms: vary in which muscle groups are affected and in age of onset.

Common early signs include muscle weakness, delayed motor milestones in children, frequent falls, difficulty rising from the floor, and enlarged calf muscles due to fatty replacement. Cardiac and respiratory involvement are important causes of complications in many types.

Diagnosis and management

Diagnosis uses family history, clinical examination, blood tests for muscle enzymes, genetic testing and sometimes muscle biopsy. There is no universal cure. Management focuses on preserving function and quality of life through physiotherapy, orthoses and mobility aids, respiratory and cardiac monitoring, and medications such as corticosteroids for some types. Specialist care teams coordinate interventions to delay complications and maximize independence.

Research into targeted therapies — including gene-based approaches, exon skipping, and molecular treatments — is active and has produced incremental advances for certain subtypes. Ongoing clinical trials, improved supportive care, and multidisciplinary treatment have increased attention to long-term outcomes and patient-centered care in recent decades.