Definition:

Nemaline myopathy (NM) is the most common congenital myopathy inherited in an autosomal dominant or autosomal recessive manner. It is characterized by the presence of rods or nemaline bodies, which are red-purple inclusions in myofibers detected by modified Gomori trichrome technique. The hallmark symptoms are generalized muscle weakness with facial involvement or predominant involvement of proximal limb and respiratory muscles. Currently, NM is classified into six different forms: severe congenital (neonatal) form; Amish NM, intermediate congenital form; typical congenital form; childhood-onset form; and adult-onset (late-onset) form. Mutations in several genes, encoding components of the sarcomeric thin filaments, have been identified. Mutations in ACTA1 and NEB nebulin are the most common.