Duchenne Muscular Dystrophy is inherited X-recessively, which causes and affecting the male sex. The cause is a mutation in the short arm of X – the chromosome (Xr 21). With disorders in this locus, a defect occurs in the protein dystrophin, which is involved in the construction of the sarcolemma of muscle fibers. This protein regulates the transport of calcium, in the cell membrane, in its absence or reduction, an increased import of Ca 2+ ions occurs.
What are the clinical manifestations?
- The disease affects the male sex, and the first symptoms are almost imperceptible, but they are observed already in the nursing period – slow turning, sitting and walking.
- Proximal muscle weakness gradually progresses and around 2-3 years of age children change their gait, starting to wobble, having difficulty climbing stairs and standing up from a squatting position.
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- The Gowers symptom is observed – when they start to stand up from a lying position, they help themselves with their hands, leaning on their lower limbs.
- Gradually occurs growth of connective tissue in the calves, leading to pseudohypertrophy.
- Symmetrical weakness develops in the limbs, mainly with the proximal muscle groups.
- Contractures and deformations develop quickly. Over time, scoliotic changes of the spine, a deformation in the shape of the long bones, are formed as a result of the contractures.
- From the beginning as a result of early contracture of the m.triceps sure, children start to walk on their toes. Subsequently, walking becomes increasingly difficult and they stop walking between 8 and 12 years of age .
- Movement in the distal muscle groups is preserved, they can use a pencil, keyboard, etc.
- Gradually, the respiratory muscles are affected, as a result of which the development of severe respiratory infections begins.
- Gradually the heart muscle is also affected, with the development of cardiomyopathy, and after the age of 18, the effect covers all patients.
What are the lab changes?
- Highly elevated values of creatinine phosphokinase (CPK), 100 and more times above normal, are found.
- Myopathy is established by electromyography.
- After establishing elevated values of CPK, a genetic study of the DMD-gene is necessary, in the absence of a mutation, a muscle biopsy and immunohistochemical analysis for dystrophin are performed.
What is the treatment?
There is no etiological treatment and there is no method to slow down the progression of the disease.
- The therapy is aimed at preventing complications and improving the quality of life.
- The diet should be consistent with the limited motor activity.
- Contractures are prevented and overcome with physiotherapy and surgical intervention if necessary.
- Quick and adequate treatment of respiratory infections is important, as well as prevention. Influenza vaccinations are indicated.
- The application of corticosteroids is possible, which slow down muscle degeneration and improve the long-term prognosis. But they are associated with severe side effects, including osteoporosis, weight gain and the risk of infections, which alter the positive effect.
Medico-genetic consultation with the mother is mandatory in case of subsequent pregnancy.
Source: puls.bg