Muscular Dystrophy
| ABOVE: Normal(A)and FSHD(B)myoblasts. The FSHD cells are swollen and vacuolated in comparison to normal myoblasts. Normal(C)and FSHD(D)myotubules. FSHD myotubules are disorganized compared to normal cells. (Wright-Giemsa stain, 20X). |
Muscular dystrophies are a group of inherited, primary diseases of muscle (i.e., the muscle tissue itself is not normal) characterized by progressive loss of strength in specific muscle groups. The muscle degenerates (atrophies) and is replaced by fat and/or connective tissue. The muscular dystrophies vary with regard to the age of onset, speed of progression, and ultimate outcome (ranging from mild disability to death). Within the past 15 years, a large number of genes associated with particular muscular dystrophies have been identified, and more are being investigated. Understanding the causes of muscular dystrophies will be improved when researchers have classified the types of muscle proteins that are disrupted by the disease.
Facioscapulohumeral muscular dystrophy (FSHD) is the third most common muscular dystrophy after Duchenne and myotonic dystrophies with an estimated prevalence of 1:20,000. This disease results in severe disability in 15-20 percent of affected individuals. Clinical diagnosis of FSHD is based on the presence of weakness in face, upper arms, and shoulders. FSHD is inherited in a dominant manner although as many as a third of cases have no family history. The mutation associated with FSHD is located on human chromosome 4. So far, though, this has not led to the immediate identification of a single gene that causes the disease. Rather, researchers now assert that the disease may result from disruption of the overall structure of a particular region of chromosome 4. PNR&D Investigators are exploring the causes of FSHD by comparing gene expression in muscle cells collected from healthy and FSHD human muscle samples.
