Although focal peripheral cap areas with myofibrillar disruption and thickened Z lines are associated with defects in the TPM2 and TPM3 genes (Marttila et al. 2014), they have also been described in association with defects in other genes associated with nemaline rods, ACTA1, NEB and MYPN. Both cap-like areas and rods can be present in the same sample and are part of the spectrum of Z-line abnormalities in nemaline myopathies (Malfatti et al. 2013). This evidence concerns the gene MYPN and nemaline myopathy.