PAPSS2 (3'-Phosphoadenosine 5'-Phosphosulfate Synthase 2): PAPSS2 is a gene that encodes an enzyme essential for producing PAPS (3'-phosphoadenosine 5'-phosphosulfate), a crucial sulfate donor in various sulfation reactions. It plays a key role in the metabolism of hormones, drugs, and other molecules. Mutations in PAPSS2 can impact skeletal development and cause disorders such as spondyloepimetaphyseal dysplasia.