What is FSHD?
Symptoms of FSHD
Facioscapulohumeral dystrophy (FSHD) is a muscle weakening and wasting disease affecting skeletal muscles. The name facioscapulohumeral describes the muscles that are usually affected first: the muscles of the face (facio), those around the shoulder blade (scapulo) and upper arm (humeral). Symptoms of FSHD may occur in early childhood, but most patients present with these symptoms during their teens.
Weakened facial muscles leads to a lack of facial expression, such as smiling, causing problems with non verbal communication. Lifting the arms above shoulder level is often impossible, as is lifting or carrying weights. The disease can spread to the foot flexors, leading to problems with walking and a higher chance of falling. Stomach and back muscles are often affected too, which can lead to a protruding belly and greatly altered posture, which can cause back pain. When upper leg and hip muscles become affected, it becomes progressively more difficult to walk, climb stairs and stand up from a chair or the toilet. About twenty percent of patients cannot walk at all and are thus fully dependent on a wheelchair for mobility, but many more with FSHD use a wheelchair or a motorized scooter to travel longer distances than they are able to on foot.
There is no cure or treatment for FSHD, but, with enough available funds, we believe a treatment can be found.
Pain and severe fatigue
Pain and severe fatigue are frequent in FSHD. Many have lower back pain, pain in the shoulders and pain in the legs. Due to severe fatigue, someone with FSHD can often do far less than they want to do.
Hearing loss and retinal problems
In addition to muscle weakness, FSHD can lead to high frequency hearing loss and retinal vasculopathy. Usually these features do not lead to disease symptoms, except in the most severely affected individuals.
Incidence of FSHD
FSHD is one of the most common muscular dystrophies occuring in 1 in 14,000 individuals.
What causes FSHD?
FSHD is caused by a region of repetitive DNA called “D4Z4” on the tip of chromosome 4. Most patients are missing a chunk of this repetitive DNA, which causes the repeat region to have a more 'open' structure than in healthy individuals. A small percentage of patients are not missing that chunk of DNA, but nevertheless their DNA in the D4Z4 region has an open structure.
The open structure is presumed to cause a gene called DUX4 to become active from the last repeat in the muscles of people with FSHD. In healthy people's muscles this DUX4 is inactive. DUX4 is a so-called transcription factor, which means it influences the activity of other genes. In line with this, research has shown that in FSHD many genes have aberrant activity. It is, however, still unknown which of these genes are directly responsible for the muscle weakening.
Scientists are studying DUX4 and its targets, as well as potential molecules that could help block its harmful effects. You can read a summary of such research in layman's terms or for an example of ongoing research we kindly refer you to information provided by the Muscular Dystrophy Campaign about research in Dr. Peter Zammit's group at King's College London.
Early onset or infantile FSHD (iFSHD)
Children below 10 years of age can also be affected by FSHD. This is called early onset or infantile FSHD (iFSHD) and is considered the most severe form of the disease. It is rapidly progressive and severely debilitating and is caused by the same genetic defect on chromosome 4, except that the size of the missing piece of DNA is greater. Because of its early onset - often at birth - infantile FSHD poses distinct challenges. In addition to having more severe muscle weakness, children with infantile FSHD have greater non-muscular symptoms. Hearing loss needs to be recognized and addressed. Due to hearing loss and lack of facial expression there is a risk that children will be misdiagnosed as having cognitive development problems. Speech therapy can help treat problems with speaking and eating. Those with infantile FSHD should be screened for breathing problems and retinal telangiectasia, and treated appropriately.
Scientific publications
Layman's terms summaries of scientific publications about FSHD can be found on our Scientific Publications In Layman's Terms page. A comprehensive list of scientific publications can be found on PubMed.