Heterogeneity of the factor IX locus in nine hemophilia B inhibitor patients

J Clin Invest. 1987 Mar;79(3):746-53. doi: 10.1172/JCI112880.


DNA from nine hemophilia B patients who produce anti-factor IX inhibitors (antibodies), including two brothers, was analyzed by the Southern blotting method and hybridization with factor IX cDNA, intragenomic, and 3'-flanking probes. Two inhibitor patients were shown to have total deletions of the factor IX gene. Two other inhibitor patients, the brothers, were shown to have a presumably identical complex rearrangement of the factor IX gene involving two separate deletions. The first deletion is of approximately 5.0 kb and removes exon e. The second deletion is between 9 and 29 kb and removes exons g and h but leaves exon f intact. An abnormal Taq I fragment at one end of the deletion junctions acted as a marker for the inheritance of hemophilia B in the patients' family. Five other inhibitor patients have a structurally intact factor IX gene as detected by this method. Our studies indicate that whereas large structural factor IX gene defects predispose hemophilia B patients to developing an anti-factor IX inhibitor, the development of an inhibitor can be associated with other defects of the factor IX gene.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA / genetics*
  • DNA Restriction Enzymes
  • Deoxyribonucleases, Type II Site-Specific*
  • Exons
  • Factor IX / genetics*
  • Hemophilia B / genetics*
  • Humans
  • Male
  • Mutation
  • Nucleic Acid Hybridization
  • Promoter Regions, Genetic


  • Factor IX
  • DNA
  • DNA Restriction Enzymes
  • Deoxyribonucleases, Type II Site-Specific
  • TCGA-specific type II deoxyribonucleases