An Overview of the Other Muscular Dystrophies: Underlying Genetic and Molecular Mechanisms

Abstract

Muscular dystrophies (MD) refer to a heterogeneous group of disorders associated with ongoing muscle degeneration and regeneration, leading to progressive weakness. The distribution of weakness includes a limb-girdle pattern, with shoulder and hip girdle muscle involvement; a humeroperoneal pattern, with predominantly triceps, biceps, and peroneal muscles weakness; or a distal pattern, with distal weakness in the legs and arms. Traditionally, the classification of MD is based on a combination of clinical and pathological criteria, including age of onset and distribution of muscle weakness, the extent of disease progression, associated symptoms, systemic features, family history, serum creatine kinase, muscle histology, as well as electromyography and nerve conduction studies. Increasingly, the diagnosis of MD requires genetic confirmation, as there can be considerable variations and overlaps in the clinical phenotypes. This chapter aims to provide an overview of the myotonic dystrophies, limb-girdle muscular dystrophies, and congenital muscular dystrophies. Duchenne and Becker muscular dystrophy as well as facioscapulohumeral dystrophy are discussed in other chapters.