ACTA1 and nemaline myopathy: For all five of these variants, the homologous residues in ACTA1 have been reported38,39,40,41,42,43 to be perturbed in infants with autosomal dominant severe congenital nemaline myopathy (Figure 2), leading to death before 1 year of age, an observation that further suggests that these residues play a critical role in sarcomere function.