Variant of intron 22 inversions in the factor VIII gene in severe hemophilia A

Blood Coagul Fibrinolysis. 1997 Oct;8(7):445-9. doi: 10.1097/00001721-199710000-00011.


Recurrent DNA inversions, which disrupt the factor VIII (FVIII) gene, generally occur between a region of intron 22 (int22h) and one of two homologous copies of this region, located 300 to 400 kb telomeric to the FVIII gene. This report describes a patient with severe hemophilia A and a high level inhibitor with atypical hybridization patterns. A Bcl I Southern blot assay was altered to 17.5, 16, and 14 kb. His mother and two out of four aunts tested had normal and abnormal restriction patterns which led to a total of five different fragments, suggesting that they were carriers. The Xba I plus Kpn I restriction fragment-length polymorphism in intron 22 by Southern blotting using the same probe (probe a) yielded the 6.2 kb polymorphic band, with a clearly separated 6.6 kb band from the non-factor VIII region; an alternative int22h hybridization probe (probe x) detected no additional fragment. These results suggest that probe a as well as probe x could recognize an intron-22-sized fragment. This report shows a variation in the number of int22h copies although we could not find the inversion junction.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Chromosome Inversion*
  • Factor VIII / genetics*
  • Hemophilia A / genetics*
  • Humans
  • Introns / genetics
  • Male
  • Pedigree


  • Factor VIII