32. Facioscapulohumeral Dystrophy
Definition
Facioscapulohumeral dystrophy (FSHD) is a relatively benign, autosomal dominant form of muscular dystrophy that produces marked atrophy of the facial musculature, shoulder girdle, and arm. Facioscapulohumeral dystrophy is also known as Landouzy-Dejerine dystrophy.
Incidence
The incidence of FSHD is approximately 1:20,000. It is the third-most common muscular dystrophy, with a higher frequency in males than females.
Etiology
The specific genetic defect that produces FSHD is not yet known. Several mechanisms have been proposed, including:
1. Position variegation effect on a proximal gene(s)
2. Mutation of a functional gene within the Kpnl repeat units
3. A mitochondrial dysfunction
4. Increased susceptibility to myoblastic oxidative stress
Signs and Symptoms
