PIGP (Phosphatidylinositol Glycan Anchor Biosynthesis Class P) is a Protein Coding gene. The PIGP gene, located on 21q22.13, is conserved in chimpanzee, dog, cow, mouse, rat, chicken, zebrafish, and frog. This gene encodes an enzyme involved in the first step of glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells that serve to anchor proteins to the cell surface. The encoded protein is a component of the GPI-N-acetylglucosaminyltransferase complex that catalyzes the transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI). This gene is located in the Down Syndrome critical region on chromosome 21 and is a candidate for the pathogenesis of Down syndrome. This gene has multiple pseudogenes and is a member of the phosphatidylinositol glycan anchor biosynthesis gene family.