SELENON encodes selenoprotein N (SelN), a selenocysteine-containing redox enzyme located in the endoplasmic reticulum membrane where it colocalizes with mitochondria-associated membranes 1. The protein functions as a critical regulator of cellular redox homeostasis and calcium handling in skeletal muscle. SelN is essential for muscle regeneration and satellite cell maintenance, playing a key role in early satellite cell activation processes 2. The protein regulates glutathione redox pathways and cellular energy metabolism, with SelN-deficient myoblasts exhibiting altered glutathione homeostasis and abnormal metabolic patterns 1. SelN also appears to influence ER calcium homeostasis through its role in oxidative protein folding processes 3. Mutations in SELENON cause SELENON-related myopathy (SELENON-RM), a congenital myopathy characterized by axial muscle weakness, progressive respiratory insufficiency, and multiminicore pattern on muscle biopsy 1. This condition affects approximately 15% of patients with cardiac abnormalities, primarily secondary right ventricular dysfunction due to pulmonary complications 4. The disease demonstrates the critical importance of SelN in maintaining skeletal muscle function and cellular homeostasis 5.