Limb girdle muscular dystrophies: The clinicopathological viewpoint

Limb girdle muscular dystrophies (LGMD) are characterized by involvement of the pelvic and shoulder girdles, classically with an onset in the second or third decade and a slow progression as opposed to Duchenne muscular dystrophy. In fact, there are many clinical variants that are related to this broad definition. For the past 13 years and since the discovery of calpain-3 as the underlying defect in LGMD 2A in 1995, a number of different genes have been found to cause LGMD; some of whose encoding proteins are located either in the sarcolemma, nucleus, cytosol or in the extra-cellular matrix. Very little is known regarding a possible common pathogenesis between all these entities. The current nomenclature of LGMDs, although a bit confusing, is still necessary to continue the establishment of homogeneous cohorts of patients and to look for unknown genes. The diagnosis of LGMD is nowadays based on a complementary clinical, immunocytochemical and genetic approach that is best achieved in specialized myology centers. In this context, India can make a significant contribution to improve the routine diagnosis in LGMD patients and to find new LGMD genes in genetic isolates. Therapeutic prospects in LGMD, although quite exciting, remain at a preliminary stage, especially those with gene-therapy orientation