Duchenne and Becker's myocardial infarction

Duchenne and Becker's disease are diseases with an X-linked recessive type of inheritance, which are characterized by progressive proximal muscle weakness due to degeneration of the muscle fibers. Becker's myodystrophy is characterized by a later onset and less severe manifestations.

The diagnosis is presumed clinically and is confirmed when determining the protein (dystrophin), which is the product of a mutated gene. Treatment focuses on maintaining the function with the help of physiotherapy and the use of fixatives and orthopedic devices; Some patients with a pronounced decrease in function are prescribed prednisolone.

[1], [2], [3], [4], [5], [6]

What causes myocardial Duchenne and Becker?

Duchenne and Becker's dystrophies are caused by mutations at the locus of Chr21. In Duchenne's dystrophy, the mutation leads to the absence of dystrophin, the protein of the cell wall membrane. In Bekker's dystrophy, an anomalous dystrophy or an inadequate quantity is synthesized as a result of the mutation. Duchenne's myodystrophy occurs in 1/3000 live-born boys; Becker's dystrophy is present in 1/30 000 live-born boys.

Symptoms of myocardial infarction Duchenne and Becker

Duchenne's myodystrophy usually occurs between the ages of two and three. The weakness of the proximal musculature develops, usually starting from the lower extremities. Children have a gait waddling, gait with support on socks and lordosis. Such children often fall, it is difficult for them to run, jump, climb the stairs and from the floor. The disease of Duchenne's myodystrophy is steadily progressing, there are flexion contractures of the joints and scoliosis. Developed dense pseudohypertrophy (fat and fibrous replacement of individual enlarged muscle groups, especially the calf muscles). Most patients are chained to a wheelchair by the age of 12 and die from respiratory complications by the age of 20. Heart damage is usually asymptomatic, despite the fact that 90% of patients have ECG changes. A third of patients have a slight non-progressive decline in intelligence, mostly with a violation of verbal rather than non-verbal tests.

Becker's myocardial infarction manifests itself clinically significantly later, and its symptoms are less pronounced. Patients are usually able to walk for at least 15 years, and many remain walking in adulthood. Most affected patients live more than 30-40 years.

Diagnosis of Duchenne and Becker's myodystrophy

The diagnosis is suspected according to the characteristic clinical manifestations, the age of the onset, the family history, indicating the hereditary type of inheritance. Symptoms of myopathy are detected with electromyography (rapidly evoked, short low-amplitude motor potentials) and muscle biopsies (necrosis and pronounced differences in the dimensions of muscle fibers). The level of creatine kinase can be increased up to 100 times in comparison with normal.

The diagnosis is confirmed by the analysis of dystrophin in immune staining. Dystrophy is not defined in patients with Duchenne dystrophy; in patients with Becker dystrophy, dystrophy is usually abnormal (with a lower molecular weight) or is detected in lower concentrations. DNA analysis in peripheral blood leukocytes to detect mutations can also confirm the diagnosis of anomalies of the dystrophin gene (deletion and duplication in approximately 65% and point mutations in approximately 25% of patients).

Carrier identification and prenatal diagnosis are possible using conventional methods (pedigree analysis, determination of creatine kinase, fetal sex determination) in combination with DNA analysis and immune staining of muscular tissue with antibodies to dystrophin.

[7], [8], [9], [10], [11], [12]

Treatment of Duchenne and Becker's myodystrophy

There is no specific treatment for Duchenne and Becker's myodystrophy. Moderate exercises are encouraged as long as they are possible. Passive exercises can extend the period when the patient can walk and does not need a wheelchair. Fixing the leg with the grip of the knee and foot helps to prevent flexion during sleep. Orthopedic leg restraints can temporarily contribute to keeping the patient walking or standing. Obesity should be avoided; the need for calories in such patients is lower than normal for their age. It also shows the direction of such a patient and his family to consult a geneticist.

Daily intake of prednisolone does not lead to long-term clinical improvement, but it probably slows the course of the disease. There is no consensus on the long-term effectiveness of prednisolone. Gene therapy is currently unavailable. Sometimes, Duchenne and Becker's myodystrophy require corrective operations. In the presence of respiratory failure, non-invasive respiratory support (for example, nasal mask) may be used. More and more approval is won by elective tracheostomy, which allows the patient to live more than 20 years.