Mutations in genes coding for six different proteins associated with muscle thin filaments have been shown to cause nemaline myopathy, namely slow muscle α-tropomyosin (TPM3) [18], nebulin (NEB1) [19], skeletal muscle α-actin (ACTA1) [20], troponin T1 (TNNT1) [21], slow muscle β-tropomyosin (TPM2) [22] and muscle-specific cofilin (CFL2) [23]. This evidence concerns the gene CPSF4 and nemaline myopathy.