Nemaline myopathy is a heterogenous form of congenital myopathy characterised by a variable spectrum of clinical features, predominated in the severe form by profound muscle hypotonia and weakness accompanied by respiratory insufficiency. The clinical variability, with differing age of onset and severity of symptoms makes the diagnosis of nemaline myopathy difficult in some cases. Severe forms of nemaline myopathy may be caused by mutation of a number of different genes: skeletal muscle actin (ACTA1), nebulin (NEB) and alpha-tropomyosin (TPM3), all of which encode components of the sarcomeric thin filaments of skeletal muscle.