HS3ST3A1 encodes a heparan sulfate 3-O-sulfotransferase that catalyzes the transfer of sulfate groups to glucosamine residues in heparan sulfate chains, specifically targeting N-unsubstituted glucosamine linked to 2-O-sulfo iduronic acid units 1. The enzyme plays critical roles in multiple biological processes through its modification of heparan sulfate proteoglycans. In viral pathogenesis, HS3ST3A1-modified heparan sulfate serves as a binding receptor for Herpes simplex virus-1, facilitating viral entry 1. The gene shows significant clinical relevance in malaria susceptibility, where genetic variants in the HS3ST3A1 promoter region are associated with Plasmodium falciparum parasitaemia levels 23. In pregnancy complications, decreased HS3ST3A1 expression in placental tissue correlates with pre-eclampsia, maternal blood pressure, and reduced neonatal birth weight 4. The enzyme also contributes to cancer progression, particularly in multiple myeloma, where HS3ST3A1-mediated 3-O-sulfation of syndecan-1 enhances tumor aggressiveness and drug resistance 5. Additionally, HS3ST3A1 variants containing Neanderthal introgression influence human tooth crown dimensions, suggesting evolutionary significance 6. The gene's expression in dental development and its interaction with key proteins like those involved in Alzheimer's disease pathways further demonstrate its broad biological importance 1.