Coagulation factor IX (F9) genomic locus (F9)

The F9 genomic DNA locus, situated on the X chromosome at position q27.1, encodes coagulation factor IX, a vitamin K-dependent serine protease essential for the intrinsic pathway of blood coagulation [NCBI Gene, 2024]. Mutations in this locus, including point mutations, deletions, and insertions, lead to Hemophilia B (also known as Christmas disease), a condition characterized by impaired hemostasis and spontaneous bleeding into joints and muscles [StatPearls, 2023]. As a therapeutic target, the F9 locus is the focus of gene therapy and gene editing strategies designed to restore the production of functional factor IX protein. Current FDA-approved gene therapies, such as etranacogene dezaparvovec, utilize adeno-associated virus (AAV) vectors to deliver a functional F9 gene—specifically the high-activity Padua variant—to the liver [FDA, 2022]. This approach aims to convert severe hemophilia phenotypes into mild or near-normal states by establishing long-term endogenous protein expression, thereby reducing or eliminating the need for prophylactic factor replacement therapy [PubMed, 2023]. Successful targeting of this locus represents a significant advancement in precision medicine for monogenic bleeding disorders.

Other names

Factor IX geneFIX geneHEMBChristmas factor geneF9 gene

Gene replacement therapy using adeno-associated virus (AAV) vectors to deliver a functional F9 expression cassette to hepatocytes, enabling endogenous production of Factor IX protein [FDA, 2022; NIH, 2023].