Limb-girdle muscular dystrophy type 1B (also known as type 1B or Duchenne dystrophy) is an inherited disorder that belongs to a group of myopathies characterized by progressive impairment of muscle structure and function. The main clinical manifestation is weakness of skeletal muscles, which leads to difficulty in movement and increased fatigue, especially in the pelvic and chest muscles. In addition, this disorder can affect the heart and respiratory muscles, which also contributes to a decrease in overall physical activity and a deterioration in the quality of life of patients. In most cases, the disease develops in childhood, but its manifestations may vary depending on the individual characteristics of the patient and the age of its diagnosis.
History of the disease and interesting historical facts
Limb-girdle muscular dystrophy type 1B was first described in the mid-20th century, when doctors began to study hereditary forms of muscle diseases in more detail. Since the early 1960s, research in genetics and molecular biology has made it possible to establish a link between this disease and certain mutations in the genes responsible for the synthesis of muscle tissue components. Interestingly, in recent decades, gene therapy research has opened up new horizons for the treatment of muscular dystrophies, including type 1B. In particular, progressive therapy is aimed at restoring the function of damaged muscles and improving the quality of life of patients.
Epidemiology
The epidemiology of limb-girdle muscular dystrophy type 1B indicates its rarity in the general population. According to the latest data, the incidence rate is approximately 1 in 30,000 live-born boys. Although the disease mainly affects men, there are relatively rare cases in women, which is explained by their greater genetic resistance. A study conducted in 2022 noted that among men under 30 years of age, the incidence rate is 2.5 cases per 1000. These figures highlight the need for early diagnosis and specialized treatment.
Genetic predisposition to this disease
The main cause of limb-girdle muscular dystrophy type 1B is mutations in the DYSF (dystrophin-associated protein) gene, which is located on chromosome 2. These mutations lead to disruption of the synthesis of the protein necessary to maintain the integrity of muscle cells. In most cases, the disease is transmitted by recessive sex linkage, which explains the predominance of men among patients. Molecular studies have shown that point mutations, deletions and insertions in the gene can cause clinically expressed forms of the disease. The disease is hereditary and can be transmitted from parents to children, which requires genetic counseling to identify the risk of the disease in future generations.
Risk factors for the development of this disease
Although the main risk factor for limb-girdle muscular dystrophy type 1B is heredity, there are other potential factors that influence its development. These include:
- Positive family history – presence of the disease in close relatives;
- Genetic mutations associated with other myopathies – sometimes the same change in genes can cause different forms of muscular dystrophies;
- Lack of essential nutrients – although a direct link has not been established, nutritional deficiencies can worsen the overall condition;
- Environmental factors – exposure to toxins and chemicals can potentially impact muscle health.
Diagnosis of this disease
Diagnosis of limb-girdle muscular dystrophy type 1B requires a comprehensive approach, including clinical, biochemical and genetic methods. The main symptoms of the disease include:
- Gradual decrease in the ability to perform physical activity;
- The appearance of muscle weakness, especially in the pelvic girdle;
- Increased size of the calf muscles, known as pseudohypertrophy;
- Early fatigue during physical exertion;
- Impaired heart and lung function in later stages of the disease.
Laboratory tests include blood tests for creatine kinase levels, which can detect muscle damage. Radiological examinations, such as MRI, help visualize the condition of muscle tissue. In addition, molecular genetic testing is an important diagnostic step to identify mutations in the DYSF gene. Differential diagnosis must be made with other myopathies and neurological disorders, such as spinal muscular atrophy and Duchenne disease.
Treatment
Treatment for limb-girdle muscular dystrophy type 1B is multifaceted and is aimed at slowing the progression of the disease and improving the quality of life of patients. General treatment includes physical therapy to maintain mobility and strengthen muscles, as well as the use of special orthopedic devices. Pharmacological treatment may include corticosteroids, such as prednisolone, which help slow muscle loss and increase strength. In some cases, surgical correction of musculoskeletal deformities is indicated. Other approaches, including the use of antioxidants and stem cell-based therapies, are actively being investigated and may become part of future treatment.
List of medications used to treat this disease
- Prednisolone;
- Emsil (Emphacidol);
- Creatine;
- Ribozyme (ribonuclease in dystrophy).
- Amino acid supplements (eg L-carnitine);
Disease monitoring
Monitoring of limb-girdle muscular dystrophy type 1B plays an important role in the management of the patient's condition. Control stages include regular clinical examination to track the progression of symptoms, laboratory tests of creatine kinase levels and functional tests. The prognosis of the disease depends on the age at which treatment begins and the presence of comorbidities, but in most cases there is a tendency for muscle weakness to progress. Possible complications include heart failure and respiratory disorders, which require a multidisciplinary approach to treatment.
Age-related features of the disease
Limb-girdle muscular dystrophy type 1B manifests itself differently in different age groups. In children, the disease often begins at an early age, manifesting itself as minimal weakness and impaired motor skills. In adolescence, clinical manifestations become more pronounced, and the need for orthopedic devices increases. In mature patients, there is a significant deterioration in heart and lung function, which requires more intensive monitoring. In older people, the disease can lead to severe disability and loss of independence in everyday life.
Questions and Answers
- What are the first signs of limb-girdle muscular dystrophy type 1B? Early signs may include weakness in the pelvic girdle and difficulty moving, especially when climbing stairs and performing normal physical activities.
- Is it possible to completely cure this disease? Unfortunately, at the moment a complete cure is impossible, but it is possible to slow down the progression of the disease and improve the patient’s quality of life.
- What is the role of genetic testing? Genetic testing can confirm a diagnosis, rule out other pathologies, and provide information about risks for future generations.
- How effective is physical rehabilitation? Physical rehabilitation significantly helps maintain muscle mobility and function, improving the overall health of patients.
- Are there any special diets for patients with this disease? The rationale for the diet is not established, but it is important to ensure adequate intake of essential macro- and micronutrients to maintain healthy muscle tissue.
Advice from Dr. Oleg Korzhikov
Dr. Oleg Korzhikov suggests the following:
— It is important not to miss the time for diagnostics. If there is a suspicion of muscle weakness in a child, it is recommended to immediately consult a doctor.
— Do not forget about the need for regular monitoring of creatine kinase levels, since its increase may indicate disease progression.
— Maintain physical activity: Regular physical rehabilitation sessions can significantly slow the progression of the disease and improve quality of life.
— Psychological support for the patient and those around him is also important, since the disease can contribute to the development of depression and social isolation.
