The chances of a D4Z4 contraction with a 4qA allele being passed on to a child is 50% (autosomal dominant); in 30% of cases, the mutation arose spontaneously. Mutations of FSHD cause inadequate DUX4 repression by unpacking the DNA around DUX4, making it accessible to be copied into messenger RNA (mRNA). The 4qA allele stabilizes this DUX4 mRNA, allowing it to be used for production of DUX4 protein. DUX4 protein is a modulator of hundreds of other genes, many of which are involved in muscle function. How this genetic modulation causes muscle damage remains unclear.Signs, symptoms, family history, and diagnostic tests can suggest FSHD; genetic testing can provide definitive diagnosis. No intervention has proven effective for slowing progression of weakness. Screening allows for early detection and intervention for various disease complications. Symptoms can be addressed with physical therapy, bracing, and reconstructive surgery such as surgical fixation of the scapula to the thorax. FSHD affects up to 1 in 8,333 people, putting it in the three most common muscular dystrophies with myotonic dystrophy and Duchenne muscular dystrophy. Prognosis is variable. Many are not significantly limited in daily activity, whereas a wheel chair or scooter is required in 20% of cases. Life expectancy is not affected, although death can rarely be attributed to respiratory insufficiency due to FSHD.FSHD was first distinguished as a disease in the 1870s and 1880s when French physicians Louis Théophile Joseph Landouzy and Joseph Jules Dejerine followed a family affected by it, thus the initial name Landouzy–Dejerine muscular dystrophy.
Outcome measures
Ways of measuring the disease are important for studying disease progression and assessing the efficacy of drugs in clinical trials. Quality of life can be measured with questionnaires, such as the FSHD Health Index. How the disease affects daily activities can measured with questionnaires, such as the FSHD‐Rasch‐built overall disability scale (FSHD-RODS) or FSHD composite outcome measure (FSHD-COM). Electrical impedance myography is being studied as a way to measure muscle damage. Muscle MRI is useful for assessment of all the muscles in the body. Muscles can be scored based on the degree of fat infiltration. References
External links
World FSHD Alliance: FSHD patient advocacy organizations across the world
list of clinical trials for FSHD, Clinicaltrials.gov. fsh at NIH/UW GeneTests