SCLY (selenocysteine lyase) is a critical enzyme in selenium metabolism that catalyzes the decomposition of L-selenocysteine to L-alanine and elemental selenium 1. The enzyme functions primarily in the cytosol and Golgi apparatus, playing an essential role in selenium recycling and selenoprotein biosynthesis 23. SCLY produces selenide, which serves as a substrate for selenophosphate synthetase 2 (SEPHS2) to generate selenophosphate, the essential selenium donor for Sec-tRNA biosynthesis 2. The enzyme's expression is tissue-specifically regulated by selenium levels, with liver being the primary site of production 1. SCLY has emerged as clinically significant in multiple disease contexts. It contributes to ferroptosis resistance, with upregulation protecting against renal ischemia-reperfusion injury through enhanced selenium recycling 3. Large-scale proteomic studies have identified SCLY as a biomarker associated with asthma risk, psoriasis development, diabetic complications, and hepatocellular carcinoma risk 4567. These findings position SCLY as both a metabolic regulator and potential therapeutic target across diverse pathological conditions involving selenium homeostasis and oxidative stress responses.