Synonyms
Duchenne muscular dystrophy, Duchenne’s disease, Duchenne Muscular Dystrophy
Summary
Duchenne muscular dystrophy is the most common hereditary muscular dystrophy besides “myotonic dystrophy” and shows a marked muscular atrophy already in early childhood. This is caused by a mutation in the genetic blueprint for an important structural protein of the muscle, dystrophin. Because of the inheritance, almost exclusively men are affected. The disease leads to progressive muscle atrophy and weakness, progresses rapidly and ends fatally by affecting the respiratory and cardiac muscles. Those affected usually die in early adulthood.
Definition
Duchenne muscular dystrophy is an x-linked recessive hereditary disease which, due to the absence or defect of dystrophin, an important structural protein in the muscle, leads to progressive muscle atrophy and sooner or later ends fatally.
FrequencyOccurrence
Duchenne muscular dystrophy is the most common hereditary muscle disease of childhood with a frequency of about 1:5000. Due to the x-linked recessive inheritance, almost exclusively boys are affected by the full picture of the disease, girls only develop the disease if there is no intact blueprint for dystrophin on both X chromosomes, which is extremely rare. In 2.5% of cases, female carriers of a defective X chromosome show mild symptoms such as muscle pain, mild weakness, or elevated levels of a muscle enzyme (creatine kinase, CK) in the blood.
Cause
The disease is caused by the lack of a genetic blueprint for the dystrophin protein on the X chromosome. Usually, this is inherited, but a smaller part occurs spontaneously through random changes in the parental genetic material. In about 5% of the cases, there is still a small residual production of dystrophin which is, however, not sufficient to maintain muscle function and structure.
The absence of this important structural protein of the muscle cell leads to instability of the muscle cell membrane (“muscle cell skin”) and increased membrane permeability. As a result, harmful substances can penetrate the muscle cell unhindered, and on the other hand, important substances of the cell are lost. Over time, the damage accumulates and leads to progressive cell damage and destruction in the muscles. This leads to the clinical picture of Duchenne muscular dystrophy. The lost muscle cells are partly replaced by fat cells which leads to an apparent enlargement of the affected muscles in some parts of the body (pseudohypertrophy).
