The Christmas factor, or factor IX, is a protein whose first case of deficiency was discovered in the 1950s in a young patient named Stephen Christmas. Factor IX is a critical enzyme for the formation of stable blood clots. Deficiency of factor IX results in hemophilia B.

colors by secondary structure util.mroll 1, 180, 1 X-RAY DIFFRACTION 1.70 Å BakR d0mains xmas.tree limited 500 eds. only ever minted