Congenital myopathy is a term for any muscle disorder present at birth. By this definition the congenital myopathies could include hundreds of distinct neuromuscular syndromes and disorders. In general, congenital myopathies cause loss of muscle tone and muscle weakness in infancy and delayed motor milestones, such as walking, later in childhood. Three distinct disorders are definitively classified as congenital myopathies: central core disease, nemaline rod myopathy, and centronuclear (myotubular) myopathy. Central core disease is a dominantly inherited genetic disease characterized by mild leg weakness appearing in infancy. This weakness does not progress with age, but leads to delay in walking. Nemaline rod myopathy is a dominantly or recessively inherited, genetic disease characterized by infantile muscle weakness and loss of muscle tone, accompanied by problems in suckling or feeding, delay in walking, and occasionally respiratory problems. Other characteristics surface with maturity, such as reduction of muscle bulk, weakness of the trunk and limbs, and development of a long and abnormally shaped face with a protruding jaw. Muscle weakness and wasting may progress slowly throughout life. Centronuclear (myotubular) myopathy is an inherited genetic disorder characterized by muscle weakness and loss of tone present at birth or by development of muscle weakness later in infancy. Weakness gets gradually worse and can become moderately severe. Infants may have ophthalmoplegia or paralysis of the eye muscles.

Treatment involves supportive measures to help patients cope with the symptoms of congenital myopathies.

Patients with central core disease generally have a normal life expectancy with non-progressive muscle weakness. Patients with nemaline rod myopathy may have a normal life expectancy with progressive weakness, or may die early in infancy from respiratory distress depending upon the severity of the disorder. Patients with centronuclear (myotubular) myopathy generally have a poor prognosis and suffer an early death, usually in infancy.

Prepared by the National Institutes of Health