ARSF (arylsulfatase F) is an X-linked gene located in the Xp22.3 region that encodes a functional arylsulfatase enzyme 1. The protein exhibits heat-labile arylsulfatase activity toward the artificial substrate 4-methylumbelliferyl sulfate and is not inhibited by warfarin, distinguishing it from the related ARSE gene 1. ARSF shares a highly conserved intron/exon organization with three other Xp22.3 sulfatase genes (ARSC, ARSD, ARSE), suggesting they arose from ancestral duplication events and represent a related subfamily of proteins 1. The gene contains conserved catalytic domain residues, metal-binding sequences, and signal peptides characteristic of functional sulfatases 2. ARSF localizes to the extracellular exosome and endoplasmic reticulum lumen, suggesting roles in protein secretion and extracellular metabolism. Recent genome sequencing studies identified ARSF as a novel candidate risk gene for autism spectrum disorder in a Qatari population with high consanguinity, appearing in homozygous form in affected individuals 3. Additionally, ARSF was identified as a key differentially expressed gene in psoriatic skin tissue, implicating it in inflammatory skin disease pathogenesis 4. However, the physiological substrates and specific metabolic functions of ARSF remain largely unknown.