SELENON and myopathy: SEPN1-RM predominantly manifests as cervico-dorsal spinal rigidity that differs from the rigid spine in myopathies caused by mutations in LMNA (Quijano-Roy et al., 2008), EMD (Kubo et al., 1998), COL6 (Bönnemann, 2011), or RYR1 (Bharucha-Goebel et al., 2013).