The diagnosis of these conditions should be suspected if EMG evaluation shows small-amplitude, brief-duration motor unit potentials with or without denervation potentials. Distinction among them can not be made on clinical grounds, although some features may suggest a particular condition. Skeletal anomalies (high arch palate, long dysmorphic face, and pectum excavatum or pectum carinatum) may occur in nemaline myopathy. The presence of ptosis, ophthalmoplegia, and facial weakness suggests myotubular myopathy. Nemaline and myotubular myopathy may produce severe neonatal weakness and hypotonia. Facial muscle is usually not affected in central core disease. Fibrillations are more frequent in myotubular and nemaline myopathies. The congenital myopathies with typical microscopic findings include disorders with autosomal dominant, autosomal recessive, or X-linked inheritance. Treatment is supportive.