HSD17B12 (hydroxysteroid 17-beta dehydrogenase 12) is a multifunctional enzyme that primarily catalyzes the reduction of 3-ketoacyl-CoA to 3-hydroxyacyl-CoA in the fatty acid elongation pathway, contributing to very long-chain fatty acid (VLCFA) synthesis in the endoplasmic reticulum 1. The enzyme plays a crucial role in arachidonic acid metabolism, serving as a precursor for prostaglandin synthesis 2. In reproductive biology, HSD17B12 is broadly expressed in ovarian tissues and is essential for female fertility, as haploinsufficiency in mice results in subfertility, defective meiotic arrest, and reduced prostaglandin levels 2. Additionally, HSD17B12 can contribute to testosterone biosynthesis in mice, compensating for HSD17B3 deficiency 3. The enzyme demonstrates clinical significance across multiple disease contexts: it is upregulated in type 2 diabetes pancreatic islets 4, shows increased expression in high-grade ovarian cancers correlating with COX-2 expression 5, and genetic variants are associated with neuroblastoma risk through effects on lipid metabolism 6 and head/neck cancer susceptibility 7. These findings highlight HSD17B12's multifaceted roles in lipid metabolism, steroid biosynthesis, and disease pathogenesis.