PIGA and paroxysmal nocturnal hemoglobinuria: Piga (phosphatidylinositol glycan anchor biosynthesis, class A) is a gene related with paroxysmal nocturnal hemoglobinuria and encodes a protein required for synthesis of N-acetylglucosaminyl phosphatidylinositol, the first intermediate in the biosynthetic pathway of a glycolipid on blood cells and to anchor proteins to the cell surface [58].