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Facioscapulohumeral muscular dystrophy (FSHD) is a type of muscle disorder like muscular dystrophy (MD). It mainly affects the face, shoulders, and upper arms, but it can also involve other muscles throughout the body. Over time, this disorder may lead to changes in movement and posture, and sometimes to chronic (long-term) pain.
This article will discuss what FSHD is. You’ll learn about FSHD symptoms, diagnosis, and treatment options that can help manage the condition and improve quality of life.
FSHD is a genetic muscle disease that causes muscle weakness, which slowly gets worse over time. The name describes the areas it affects the most:
Muscle weakness usually appears on one side of the body more than the other. Symptoms can start at any age, from childhood to adulthood, and tend to slowly progress over time.
FSHD happens when a gene called double homeobox protein 4 (DUX4), which is normally silent in muscles, becomes abnormally active. When DUX4 is turned on by mistake, it damages muscle fibers and leads to muscle loss. The condition is inherited in an autosomal dominant pattern. This means that a parent with FSHD has a 50 percent chance of passing it on to each child, though some cases occur through new genetic changes.
There are two main types of FSHD. They’re called FSHD type 1 (FSHD1) and FSHD type 2 (FSHD2).
FSHD type 1 is the most common, affecting about 95 out of every 100 people with FSHD. It happens when a small section of DNA on chromosome 4 is missing or shorter than usual. This mutation (change) lets the DUX4 gene turn on inside muscle cells, where it shouldn’t be active.
FSHD type 2 is less common. It usually involves a problem with another gene called SMCHD1. Normally, the SMCHD1 gene helps keep DUX4 turned off. When it doesn’t work properly, DUX4 becomes active and damages muscle tissue.
Both type 1 and type 2 FSHD cause similar symptoms.
Researchers estimate that FSHD affects between 1 in 14,000 and 1 in 20,000 people. However, new studies using improved genetic testing suggest the true number may be higher.
One large study in the Netherlands found a rate of FSHD of about 1 in 8,000 people. This could mean that as many as 40,000 people in the U.S. and more than 850,000 worldwide may be living with FSHD.
FSHD symptoms usually begin by the age of 20 for men and age 30 for women. However, in some, weakness may appear as early as infancy, while others may not develop symptoms until middle age. A few people may have such mild symptoms that they don’t even realize they have the condition. It’s common for signs and symptoms to be asymmetric, meaning one side of the body is affected more than the other.
Early signs may include trouble smiling, whistling, or even closing the eyes completely, as the muscles around the eyes and mouth tend to be affected most. Some people may notice that their eyelids remain partly open during sleep. Weakness in the muscles that hold the shoulder blades in place can cause them to “wing out” from the back. This is also known as scapular winging, and it can make it difficult to raise the arms above the head or lift objects.
As FSHD progresses, muscles of the abdomen (belly), hips, and legs may weaken. This can lead to a curved lower back (lordosis), a protruding abdomen, or difficulty standing, climbing stairs, or walking long distances. Some people experience “foot drop,” where the front of the foot drags while walking.
FSHD can also affect other body systems. Some people develop hearing loss or eye problems. For example, some people may have changes in the blood vessels of the retina, which can lead to vision loss in rare cases. Chronic pain, fatigue (extreme tiredness), and breathing difficulties can also occur, especially in more severe cases.
A rare early form of FSHD, called infantile-onset FSHD or infantile FSHD, appears in childhood and tends to progress more quickly. This form accounts for about 5 percent to 10 percent of people with FSHD and tends to happen without a family history (“sporadic”). Children may have severe facial weakness, hearing loss, and vision problems.
Doctors diagnose FSHD based on a combination of medical history, physical exams, and, sometimes, genetic testing. A neurologist (brain specialist) will look for the typical pattern of muscle weakness in the face, shoulders, and upper arms. They’ll also ask about any family history of the disorder.
A genetic test is the main way to confirm FSHD. Most people with the condition have a small missing piece of DNA on chromosome 4. This change switches on the DUX4 gene, which harms muscle cells over time.
In some families, if another close relative has already had genetic testing and the pattern of symptoms clearly fits FSHD, a DNA test may not be needed. When there’s no family history or if the symptoms are unclear, doctors may start with other, simpler tests first.
Blood tests may check for creatine kinase — an enzyme that rises when muscles are damaged. In people with FSHD, creatine kinase levels may be high but not more than five times the normal amount. Other tests, like electromyography (EMG), can show which muscles are affected. Muscle biopsies (tissue samples) are used less often today since a genetic test can confirm FSHD.
Unfortunately, there’s no cure for FSHD yet. Most treatments focus on staying active, reducing pain, and supporting weak muscles.
Physical therapy helps with flexibility and range of motion. Light to moderate exercise is generally recommended to keep muscles strong without overworking them. Specialists recommend aerobic exercise or gentle strength training to support heart health and strength. Depending on which facial muscles are affected, some people may also benefit from swallowing and breathing exercises.
Pain management may include stretching, more physical therapy, and medications. Some people report finding pain relief through techniques such as acupuncture and stress reduction techniques.
Mobility aids such as orthoses — braces or supports that help keep joints and limbs stable — can improve safety and independence. These include ankle-foot orthoses, back supports, or wheelchairs. It’s important to know that using these devices won’t cause the muscles to weaken further. In fact, a supportive brace or corset can improve mobility and endurance, helping you use your remaining strength more efficiently.
In some cases, a surgery called scapular fixation can help stabilize the shoulder blades. It involves attaching the shoulder blades to the ribs to keep them from sliding, which can make it easier to lift the arms.
Researchers are working hard to find new ways to slow or stop FSHD. Many studies focus on turning off the DUX4 gene, which is what causes FSHD symptoms.
One recent study tested an investigational drug called del-brax, which is designed to block DUX4 activity. It’s not yet approved by the U.S. Food and Drug Administration (FDA). In an early clinical trial of 39 adults, people who took del-brax had less muscle weakness and lower levels of muscle damage than those given a placebo (sugar pill). The treatment appeared safe, with mostly mild side effects. However, these are initial results, and more research is needed to confirm the findings. A larger study, called the FORWARD trial, is being planned to confirm these results in more people worldwide.
Unlike some other types of muscular dystrophy, most people with FSHD live as long as others their age. This means that for most people with FSHD, life expectancy isn’t shortened. However, in infantile-onset FSHD, which starts early in life, risks are greater because it may affect breathing or heart muscles.
On myMDteam, people share their experiences with muscular dystrophy, get advice, and find support from others who understand.
How has FSHD affected you the most? What treatments have worked best for you? Let others know in the comments below.
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