Facioscapulohumeral muscular dystrophy (FSHD) is a muscle-wasting disease associated with the progressive weakening of the muscles starting in the face, shoulders, and upper arms. It is estimated that approximately 870,000 people worldwide live with FSHD.
FSHD is a dominant genetic disease, meaning that a parent with the FSHD genetic mutation has a 50 percent chance of passing the disease on to each of their children.
Generally, the progression of the disease is fairly slow, but both the age of onset and the degree of severity of the condition can vary greatly among patients, with symptoms potentially beginning as early as infancy or as late as adulthood. The majority of patients first show symptoms of FSHD in their 20s and 30s.
What causes FSHD?
There are two different genetic mutations that can cause FSHD. Type 1, or FSHD1, which is accountable for around 95 percent of FSHD cases, is associated with deletions of gene regions called the D4Z4 units on chromosome 4. Type 2 cases, or FSHD2, are thought to be caused by genetic mutations in the SMCHD1 gene. Approximately 2 percent of all FSHD incidences are of unknown cause.
What are the symptoms of FSHD?
Early indicators of muscle weakness associated with FSHD include the inability to whistle or sip through a straw, asymmetric “winging” of shoulder blades, difficulty raising arms, and weak abdominal muscles. Approximately one in four patients with FSHD require a wheelchair by age 50, as muscle degradation extends to foot and leg muscles. FSHD does not affect respiratory or cardiac muscles, so the disease usually does not have an impact on life expectancy.
How is FSHD diagnosed?
After reviewing all symptoms as part of a physical exam, physicians may request several tests to confirm an FSHD diagnosis. Blood tests measuring the levels of creatine kinase, an enzyme that is released from damaged muscles into the bloodstream, and electromyography (EMG), which measures the ability of muscles to contract when stimulated, can help the clinical team rule out other diseases that may cause the symptoms they observe.
Genetic testing allows clinicians to look for the specific mutations that may cause FSHD. Unfortunately, there are limited commercial testing options that can identify mutations to the SMCHD1 gene.
How is FSHD treated?
There is currently no cure for FSHD. However, treatments that can help manage symptoms are available.
Anti-inflammatory drugs are often prescribed to reduce pain and to help patients increase mobility.
Regular physical activity and physical therapy are recommended to counteract the effects of muscle weakness and to maintain flexibility. Surgery to correct scapular “winging” and scoliosis associated with FSHD may also be an option for patients.
Surgery to correct scapular “winging” that helps stabilize the shoulder blades, and to help correct scoliosis, or a sideways curvature of the spine associated with FSHD, may also be options for patients.
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