This panel consists of 144 genes that have been associated with inherited neuromuscular diseases. This panel includes nuclear-encoded mitochondrial genes and select storage-disorder genes. Hereditary neuropathies, including Charcot-Marie-Tooth disease, affect the peripheral nervous system and include symptoms of muscle weakness, decreased reflexes, foot deformities, and loss of sensation. Myopathies are associated with weakness and dysfunction of predominantly proximal skeletal muscles, and wasting may occur in later stages of disease. Congenital myasthenic syndromes are caused by disruptions in the transmission of nerve signals to the muscles, and symptoms may involve weakness of muscles involved in swallowing, speech, and breathing or fatigability upon exertion. The muscular dystrophies tend to display progressive muscle weakness and atrophy due to abnormalities in the cellular maintenance of muscle membranes.
These conditions can be inherited in autosomal dominant, autosomal recessive, and X-linked patterns, and each group of disorders exhibits variable clinical presentation, age of onset, degree of severity, and disease progression. In addition to clinical evaluation and genetic testing, diagnosis for these conditions may require electromyogram and nerve conduction studies, muscle biopsy, and CPK and other biochemical testing.