Emery-Dreifuss muscular dystrophy (EDMD) is characterized by the clinical triad of: joint contractures that begin in early childhood; slowly progressive muscle weakness and wasting initially in a humero-peroneal distribution that later extends to the scapular and pelvic girdle muscles; and cardiac involvement that may manifest as palpitations, presyncope and syncope, poor exercise tolerance, and congestive heart failure along with variable cardiac rhythm disturbances. Age of onset, severity, and progression of muscle and cardiac involvement demonstrate both inter- and intrafamilial variability. Clinical variability ranges from early onset with severe presentation in childhood to late onset with slow progression in adulthood. In general, joint contractures appear during the first two decades, followed by muscle weakness and wasting. Cardiac involvement usually occurs after the second decade and respiratory function may be impaired in some individuals.

Episodic mitochondrial myopathy with or without optic atrophy and reversible leukoencephalopathy (MEOAL) is an autosomal recessive neuromuscular disorder characterized mainly by childhood onset of progressive muscle weakness and exercise intolerance. Patients have episodic exacerbation, which may be associated with increased serum creatine kinase or lactic acid. Additional more variable features may include optic atrophy, reversible leukoencephalopathy, and later onset of a sensorimotor polyneuropathy. The disorder results from impaired formation of Fe-S clusters, which are essential cofactors for proper mitochondrial function (summary by Gurgel-Giannetti et al., 2018)

Autosomal recessive limb-girdle muscular dystrophy-26 (LGMDR26) is a muscle disorder characterized by adult-onset weakness that primarily affects the proximal muscles of the lower limbs. The disorder is slowly progressive, with later involvement of the upper limbs and fatty replacement of muscle tissue apparent on MRI. Some patients may have calf hypertrophy. Serum creatine kinase is significantly elevated, and skeletal muscle biopsy shows typical dystrophic features with normal ultrastructural findings. There is no cardiac or respiratory involvement (summary by Vissing et al., 2019). For a discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600).

Congenital muscular dystrophy-dystroglycanopathy with impaired intellectual development (MDDGB15) is characterized by elevated serum creatine kinase, developmental delay, epilepsy, impaired intellectual development, and brain abnormalities (Fu et al., 2019). For a discussion of genetic heterogeneity of congenital muscular dystrophy-dystroglycanopathy type B, see MDDGB1 (613155).

Autosomal recessive limb-girdle muscular dystrophy-29 (LGMDR29) is a neuromuscular disorder characterized by onset of muscle weakness predominantly affecting the proximal lower limbs, although upper limb involvement also occurs. The disorder, which causes walking difficulties, is progressive and may result in loss of ambulation. Additional features include joint contractures, spinal abnormalities, and significant restrictive ventilatory dysfunction. Muscle biopsy shows dystrophic and myofibrillar changes, and serum creatine kinase is increased. Rare individuals have been reported to have central nervous system involvement, including cataracts, developmental delay, and brain imaging abnormalities (Nashabat et al., 2024 and Iruzubieta et al., 2024). For a discussion of genetic heterogeneity of autosomal recessive limb- girdle muscular dystrophy, see LGMDR1 (253600).