Becker’s muscular dystrophy (BMD) is a group of a genetic condition that primarily affects the skeletal muscles used for movement and heart muscle. This condition is characterized by the muscle weakness and wasting known as atrophy. This usually affects the males and is inherited in an X-linked manner. It mostly occurs with individuals in their teens or early twenties and the symptoms vary greatly among the affected individuals. The muscle weakness can progress slowly with the individual requiring a wheelchair, while some cases may also have weakened heart muscle creating life-threatening complications. Generally, these affected individuals can live into the mid or late adulthood. However, where the heart functions are not affected, with proper medical intervention, they have an almost normal life expectancy.
Causes
BMD is inherited in an X-linked recessive pattern meaning the defective gene is present in the X-chromosome. As males only have one X chromosome this defective gene can cause BMD, unlike the females who carry two X chromosomes. For females to develop this condition, both the copies of the gene have to be defective. As this is most unlikely, males are more affected than the females who tend to be the carrier of this disorder. The mother can pass the defective gene but don’t necessarily show any signs and symptoms. The mutation in the gene DMD causes this condition which is responsible for the production of a protein known as dystrophin. This protein is present in the skeletal and cardiac muscle where it protects and stabilizes the muscle fibers. The defective gene affects the protein dystrophin resulting in damage to the muscle cells. The damaged fibers may die causing muscle weakness and heart abnormalities.
Symptoms
The initial symptoms include the lack of stamina and cramping during exercise beginning in their teens or late twenties. The muscle weakness slowly progresses in the areas of thighs, shoulders, hips and pelvis causing problems with walking (toe walking). As these individual’s ability to move certain muscles are affected, they may require a wheelchair. In most cases, death occurs as the result of dilated cardiomyopathy. When the heart becomes affected the individual may feel breathless along with fluid accumulation in the lungs and swelling of the feet.
Diagnosis
A careful assessment of the medical history and the findings of physical symptoms are essential in the proper diagnosis of becker’s muscular dystrophy. The muscle and neurological system may be examined along with clinical diagnostic tests. The bone test may detect an elevated level of creatine kinase (CK) indicating muscle degeneration and muscle biopsy to observe the appearance of dystrophin protein. A molecular genetic test can identify the defective gene and confirm the diagnosis.
Treatment
There is no cure available for becker’s muscular dystrophy. However, the treatment is focused on managing the symptoms and to improve the quality of life. Active lifestyle is encouraged as inactivity such as bed rest can make this muscle condition worse. Some individuals may benefit from certain exercise to strengthen muscles. Also, weight control is essential to reduce the stress that can affect the heart and muscles. Genetic counseling may be beneficial to these individuals and their family.
References
https://rarediseases.org/rare-diseases/muscular-dystrophy-becker/
https://medlineplus.gov/ency/article/000706.htm
https://www.mda.org/disease/becker-muscular-dystrophy
https://ghr.nlm.nih.gov/condition/duchenne-and-becker-muscular-dystrophy#inheritance
