ARSK (arylsulfatase family member K) is a lysosomal sulfatase that catalyzes hydrolysis of sulfate esters in glycosaminoglycans 1. Specifically, ARSK hydrolyzes the 2-sulfate groups of 2-O-sulfo-D-glucuronate residues in chondroitin sulfate, heparin, and heparitin sulfate, acting selectively on 2-sulfoglucuronate while lacking activity against 2-sulfoiduronate 23. The enzyme functions as a 68-kDa glycoprotein with an acidic pH optimum (~4.6) and localizes to lysosomes via mannose 6-phosphate receptors 1. Biallelic ARSK loss-of-function variants cause mucopolysaccharidosis type 10 (MPS10), a lysosomal storage disorder characterized by progressive hip joint abnormalities, coarse facial features, genu valgum, and dysostosis multiplex, typically presenting around age 9.5 years without hepatosplenomegaly or cognitive impairment 45. Patients show variable dermatan sulfate excretion, and metaphyseal striation of long bones serves as a diagnostic clue 45. Beyond skeletal disease, ARSK shows cytoprotective functions; ARSK overexpression attenuates cigarette smoke-induced airway epithelial senescence via parkin-mediated mitophagy regulation, suggesting therapeutic potential for COPD 6. ARSK is recognized among carbohydrate-linked lysosomal storage diseases associated with cardiac manifestations 7.