Although cardiac involvement was considered as a result of ACTA1 mutations, the identification of NM cases with nonsense mutations, resulting in loss of giant sarcomeric protein function (extreme 5 C-terminal SH3 domain of nebulin), might explain the onset of conduction disorders, even in the absence of previous cardiomyopathy signs [2]. The gene discussed is ACTA1; the disease is nemaline myopathy.