Typical congenital nemaline myopathy

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Typical nemaline myopathy is a moderate neonatal form of nemaline myopathy (NM; see this term) characterized by facial and skeletal muscle weakness and mild respiratory involvement.

The annual incidence of NM has been estimated at 1/50,000 live births and the typical form to represent about 50% of all cases.

Disease onset is in the neonatal period. Patients have a long face, a high-arched palate and a tented upper lip. Skeletal anomalies may include kyphoscoliosis, pectus carinatum and pes cavus. In the first year of life, hypotonia and facial weakness are present and often contribute to failure to thrive and delayed motor development. Anti-gravity movements are present and respiratory muscle involvement is frequent. Nocturnal hypoxia and hypercarbia and lower respiratory tract infections are common manifestations. Joint hypermobility can be observed. In a minority of children weakness is more distal. Progression is very slow or absent and most patients are able to live an independent active life.

Typical NM is caused by mutations of the ACTA1 (1q42.13), NEB (2q22) or TPM2 (9p13) genes, and disease transmission can be autosomal recessive or dominant.

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Last updated: 10/10/2011

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