The loss of muscle mass in CKD is mainly due to two mechanisms: (i) increased muscle catabolism via the activation among other things of the ubiquitin–proteasome system, caspase-3, and lysosomes pathways and (ii) impaired muscle growth, regeneration, repair, and suppression of protein synthesis with components of abnormal myogenesis. The gene discussed is CASP3; the disease is chronic kidney disease.