ACTA1 and congenital myopathy with cores: Congenital myopathies, presenting with hypotonia at birth or in infancy and motor developmental delay, include central core disease associated with RYR1 (ryanodine receptor 1) gene variations, nemaline myopathy linked to NEB (nebulin) and ACTA1 (actin alpha 1) gene variations, and other subtypes involving at least 13 additional genes [12].