Facioscapulohumeral Muscular Dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) is a rare, progressive and variable hereditary muscle-weakening condition marked by significant pain, fatigue, and disability. It is one of the most common forms of muscular dystrophy, with onset typically in teens and young adults. FSHD affects approximately 16,000 to 38,000 people in the U.S. alone. There are currently no approved therapies to treat the underlying cause of FSHD. Current treatment approaches are focused on support for activities of daily living and mobility, improved functioning and lowering the risk of complications. They include physical therapy, exercise, pain management and orthopedic interventions.
FSHD is characterized by progressive and often asymmetric skeletal muscle loss that typically causes weakness initially in muscles in the face, shoulders, arms and trunk and progresses to weakness in muscles and in the lower body. FSHD is an autosomal dominant genetic disease caused by the abnormal expression of DUX4 (double homeobox 4), a gene involved in embryonic development but not typically expressed in adults. This abnormal expression of DUX4 protein leads to a series of downstream events that result in skeletal muscle wasting and compromised muscle function, including an inability to lift arms for more than a few seconds, loss of ability to show facial expressions, and serious speech impediments. These symptoms cause many people affected by FSHD to become dependent on the use of a wheelchair for mobility.