FSHD: The Most Common Type of Muscular Dystrophy?

Abstract

Facioscapulohumeral MD (FSHD or FSH) is a complex, inheritable muscle disease. Although frequently cited as the third most common type of MD in older reports, many newer sources rank FSHD as the most prevalent type of MD, occurring at a rate of some 7 cases/1,000 persons, as compared with DMD/BMD (5 cases/1,000) and myotonic dystrophy (4.5 cases/1,000). The identification of FSHD as the most common type of MD has important ramifications, for example, when allocating future Federal (U.S.) funding for research, and in terms of the potential market size for future FSHD treatments. FSHD has only recently attracted attention from the pharmaceutical industry, largely due to major advances in the understanding of the gene/mechanism of disease, including over-expression of a protein called DUX4. Most individuals with FSHD inherit the mutation from a parent with the disease, with 10–33  % of all FSHD cases resulting from a de novo (or sporadic) mutation. The major symptom of FSHD is progressive weakening and loss of skeletal muscles. The usual location of these weaknesses at onset is the origin of the name: face (facio), shoulder girdle (scapulo), and upper arms (humeral). There is currently no disease modifying treatment or cure for FSHD. Most treatments proposed to “treat” FSHD have not yet been tested in randomized clinical trials. These may include: hormone supplementation, protein supplements (creatinine monohydrate), or drugs used to decrease inflammation (e.g., prednisone). To better understand and validate their use, many are now being properly investigated in clinical trials.