ABSTRACT
FSHD Facioscapulohumeral Muscular Dystrophy: Clinical Medidne and Molecular Cell Biology, edited by Meena Upadhyaya and David N.Cooper. © 2004 Garland/BIOS Scientific Publishers Limited, Abingdon.
10.1 Introduction
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common hereditary myopathies with an incidence of 1 in 20 000 in the general population (Padberg, 1982). FSHD onset involves specific facial muscles, i.e. orbicularis oculi and orbicularis ori, while other muscles are spared, i.e. zygomatic, temporalis and masseter. Subsequently, muscular weakness spreads to limb girdle muscle, such as scapula fixators, and the upper part of deltoid, and to biceps and triceps. Abdominal muscles also become affected leading to a characteristic lordotic posture. Eventually, the disease extends to the muscles of the pelvic girdle. It is important to note that involvement of specific muscle groups leads to a clinical phenotype that is characteristic of FSHD. In addition, weakness displays asymmetric distribution without any correlation with handedness (Brower et al., 1992). Disease progression is unpredictable: dramatic worsening can follow periods of arrest, and considerable clinical variability has been documented. Some subjects experience very mild weakness, being almost unaware of being affected whilst others are wheelchair-dependent even within the same family. Deafness, vascular retinopathy and mental retardation can be ancillary features of the disorder (Padberg et al., 1995; Verhagen et al., 1995; Funakoshi et al., 1998).
