Duchenne and Becker muscular dystrophies are two variants of the same neuromuscular disease characterized by the absence, deficiency or alteration of a protein called dystrophin. These conditions lead to the degeneration of muscle tissue, resulting in a gradual loss of strength and reduction of motor skills.
Both forms of muscular dystrophy are caused by a mutation of a gene, located on chromosome X, which provides instructions for making dystrophin, a fundamental protein for the stabilization of the cell membrane of muscle fibres:
- Duchenne: the alternation determines the total absence of dystrophin. This leads to the weakening and eventually rupture of the cell membrane of muscle fibres, giving way to a cascade of events that leads to the death of muscle fibres
- Becker: The dystrophin is reduced or altered, but never absent
The mutation can be spontaneous (1/3 of cases) or hereditary. The transmission of the disease is linked to the X chromosome, therefore generally only males have symptoms, while females are usually healthy carriers as they have another X chromosome in addition to the mutated one.
Muscle weakness, progressive strength loss and reduction of motor skills:
- Duchenne: the first symptoms appear in early childhood. Affected children often learn to walk late; the evolution of the disease causes severe scoliosis, loss of the ability to walk by the age of 12, then loss of upper limbs mobility. Respiratory muscles and the heart are also involved, and the complications they incur in reduce the life expectancy of these patients. Rarely, there may also be a cognitive deficit.
- Becker: motor symptoms similar to Duchenne’s, but milder and with a later onset. The main issue is caused by cardiac complications, but if these are recognised and treated in time the life expectancy of these patients of these patients can be completely normal.
Cures and Therapy
Even though there is not a cure yet, the use of certain steroid medications (cortisone) can allow patients to keep motor skills longer and slow the onset of respiratory and cardiac problems.
- Respiratory care: the effectiveness of ventilation and cough are to be kept closely monitored. In case of deficits in the ability to cough naturally, respiratory physiotherapy or the use of a cough assistant, is recommended, while hypoventilation can be tackled by mechanical ventilation. Initially the ventilation is usually non-invasive (NIV), using both positive and negative pressure ventilators. When ventilation is required constantly invasive ventilation may be used.
- Heart care: periodic cardiac inspections, and use of ACE inhibitors if a cardiac deterioration is detected.