Which disorder is characterized by progressive muscle degeneration replaced by fat and fibrous tissue?

Muscular dystrophy is characterized by progressive muscle degeneration, which occurs due to the absence or deficiency of specific proteins required to form healthy muscle. This degeneration leads to muscle weakness and a gradual replacement of muscle tissue with fat and fibrous tissue. The different types of muscular dystrophy, such as Duchenne muscular dystrophy, can vary in severity and age of onset, but the common thread across all forms is the progressive nature of muscle loss and its impact on mobility and function.

In contrast, cerebral palsy primarily affects movement and posture due to brain development issues rather than muscle degeneration. Multiple sclerosis is an autoimmune disease that affects the central nervous system, leading to varied symptoms but does not involve muscle degeneration in the same manner. Rheumatoid arthritis is an inflammatory disorder that primarily affects the joints, resulting in pain and swelling but does not lead to the same types of muscular atrophy seen in muscular dystrophy. Thus, the description of progressive muscle degeneration being replaced by fat and fibrous tissue distinctly aligns with the characteristics of muscular dystrophy.