Deletion of Rictor specifically from skeletal muscle does not compromise muscle growth or function, while muscle‐specific ablation of Raptor from birth leads to a myopathy around 8 weeks of age and premature death.7 A similar late‐onset myopathy with premature death was observed after deletion of the kinase mTOR from skeletal muscle.8 While these results clearly show an important role of mTOR and Raptor in skeletal muscle, it is remarkable that no phenotype was observed during the first 6–8 weeks of postnatal growth, when skeletal muscle undergoes its most pronounced increase in size. Here, RPTOR is linked to myopathy.