In dystrophinopathies, onset of (proximal) weakness is in the first decade of life. Limb-girdle muscular dystrophies (LGMD) are a group of autosomal dominantly or recessively inherited muscular dystrophies that also present with primary proximal (limb-girdle) muscle weakness. However, most LGMDs start in the second decade of life. Myofibrillar myopathies (MFM) are a group of adult-onset myopathies, often beginning in the third or fourth decades of life. In contrast to LGMD, muscle weakness often starts in the distal muscles. Other dystrophies such as myotonic dystrophy or FSHD have often a characteristic pattern of clinical weakness but can start at any age.