Congenital myopathy

Congenital myopathy is a term that is sometimes applied to hundreds of independent neuromuscular diseases that can manifest from birth, but usually this term is reserved for a group of rare hereditary primary muscle diseases that cause muscle hypotension and weakness from birth or during the neonatal period and in some cases delay in motor development at a later age.

The five most common types of congenital myopathies include nonmyelinic myopathy, myotubular myopathy, myopathy with muscle fiber damage, congenital disproportion of muscle fiber types, and myopathy with multiple rods. They differ primarily in the histological picture, symptoms and prognosis. The diagnosis is indicated by characteristic clinical manifestations, confirming the diagnosis by carrying out a muscle biopsy. Treatment consists of physiotherapy, which can help preserve the function.

Nemyelin myopathy can be autosomal dominant or recessive and develops due to various gene mutations localized on different chromosomes. Nemalinovaya myopathy in newborns can be severe, moderate and mild. In severe lesions, patients may have weakness of respiratory muscles and respiratory failure. With moderate damage, the progressive weakness of the muscles of the face, neck, trunk and legs develops, however, the expected life expectancy can be almost normal. With slight damage, the current is non-progressive, the expected life expectancy is normal.

Myotubular myopathy is autosomal or X-linked. The most frequent autosomal variant causes mild muscle weakness and hypotension in patients of both sexes. The X-linked variant affects the boys and leads to severe weakness of skeletal muscle and hypotension, weakness of the face muscles, impaired swallowing, weakness of the respiratory muscles and respiratory failure.

Myopathy with damage to the core of muscle fibers. Type of inheritance is autosomal dominant. Most patients develop hypotension and mild weakness of proximal muscles in the period of newborns. Many also have weakness of facial muscles. Weakness does not progress, life expectancy is normal. At the same time, these patients have an increased risk of developing malignant hyperthermia (a gene associated with myopathy with a lesion of the core of muscle fibers is also associated with increased susceptibility of malignant hyperthermia).

Congenital disproportionality of types of muscle fibers is hereditary, but the type of inheritance today is poorly understood. Hypotension and weakness of the face, neck, trunk and extremities are often accompanied by skeletal anomalies and dysmorphic features. Most of the affected children show improvement with age, but a small proportion develops respiratory failure.

Myopathy with multiple rods is usually autosomnocrescent, but can also be autosomal dominant. Infants develop proximal muscle weakness, but some children develop later and include generalized muscle weakness. Progression varies considerably. 

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