PIGN (Phosphatidylinositol Glycan Anchor Biosynthesis Class N) is a gene involved in the synthesis of glycosylphosphatidylinositol (GPI) anchors, which attach certain proteins to the cell membrane. These GPI-anchored proteins are vital for functions such as cell adhesion, signal transmission, and immune system activity. Mutations in PIGN can impair GPI anchor formation, resulting in conditions characterised by developmental delays, neurological issues, and congenital defects.