Limb girdle muscular dystrophies: classification, clinical spectrum and emerging therapies

Purpose of reviewThe aim of the study was to describe the clinical spectrum of limb girdle muscular dystrophies (LGMDs), the pitfalls of the current classification system for LGMDs, and emerging therapies for these conditions.Recent findingsClose to half of all LGMD subtypes have been discovered within the last 6 years of the 21-year-period in which the current classification system for LGMD has existed. The number of letters for annotation of new recessive LGMD conditions is exhausted, and multiple already classified LGMDs do not strictly fulfill diagnostic criteria for LGMD or are registered in other classification systems for muscle disease. On the contrary, diseases that fulfill classical criteria for LGMD have found no place in the LGMD classification system. These shortcomings call for revision/creation of a new classification system for LGMD. The rapidly expanding gene sequencing capabilities have helped to speed up new LGMD discoveries, and unveiled pheno-/genotype relations. Parallel to this progress in identifying new LGMD subtypes, emerging therapies for LGMDs are under way, but no disease-specific treatment is yet available for nonexperimental use.SummaryThe field of LGMD is rapidly developing from a diagnostic and therapeutic viewpoint, but a uniform and universally agreed classification system for LGMDs is needed.