Parafibromin, also called Cell division cycle 73, is a protein which in humans is encoded by the CDC73 gene. CDC73 is part of the PAF1 complex.
Parafibromin, LEO1, PAF1, and CTR9 form the PAF protein complex, which associates with the RNA polymerase II subunit POLR2A and with a histone methyltransferase complex.
Mutations in the CDC73 gene are associated with hyperparathyroidism-jaw tumor syndrome (HPT-JT) and parathyroid carcinomas.