CACNA1S and myopathy: This is supported by the observation of a profound disturbance of the normal Cav1.1/RYR1 interaction in 1 previous patient with RYR1-related PP and other patients with recessive RYR1-related myopathies.11,20 Furthermore, the recently described CACNA1S-associated early-onset myopathy shares features of predominantly axial weakness and ophthalmoplegia with RYR1-related myopathies12 and may also feature similar reductions of the Cav1.1 protein.