ACTA1 and congenital myopathy: NM is the most prevalent congenital myopathy and is characterized by the presence of eosinophilic rod-shaped inclusions or linear bodies within the muscle fibers.[3] To date, pathogenic mutations have been identified in at least 14 genes.[10] The majority of NM patients possess mutations in the nebulin gene (approximately 50%) or the ACTA1 gene (20–30%), with ACTA1 mutations being most prevalent among those with severe congenital onset.[11–13] ACTA1 encodes skeletal muscle α-actin (42 kDa), which interacts with myosin during muscle contractions.