Mutations in the skeletal muscle alpha actin gene (ACTA1) have been associated with various skeletal muscle diseases, including actin myopathy (accumulation of actin), NM, intranuclear rod myopathy and congenital fiber type disproportion (CFTD) [72–74]. The gene discussed is ACTA1; the disease is congenital myopathy 2a, typical, autosomal dominant.