Hemophilia A due to mutations that create new N-glycosylation sites

Proc Natl Acad Sci U S A. 1992 Jun 1;89(11):4933-7. doi: 10.1073/pnas.89.11.4933.


In studying the molecular defects responsible for cross-reacting material-positive hemophilia A, we have identified two patients in whom the nonfunctional factor VIII-like protein has abnormal, slower-moving heavy or light chains on SDS/PAGE. Both patients have severe hemophilia A (less than 1% of normal factor VIII activity) with a normal plasma level of factor VIII antigen. The molecular defects were identified by denaturing gradient gel electrophoresis screening of PCR-amplified products of the factor VIII-coding DNA sequence followed by nucleotide sequencing of the abnormal PCR products. In patient ARC-21, a methionine-to-threonine substitution at position 1772 in the factor VIII light chain creates a potential new N-glycosylation site at asparagine-1770. In patient ARC-22, an isoleucine-to-threonine substitution at position 566 creates a potential new N-glycosylation site at asparagine-564 in the A2 domain of the factor VIII heavy chain. The mobility of these chains on SDS/PAGE was normal after N-Glycanase digestion and procoagulant activity was generated--to a maximum of 23% and 45% of control normal plasma. Abnormal N-glycosylation, blocking factor VIII procoagulant activity, represents a newly recognized mechanism for the pathogenesis of severe hemophilia A.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amidohydrolases / pharmacology
  • Blotting, Western
  • DNA Mutational Analysis
  • Factor VIII / genetics*
  • Factor VIII / metabolism
  • Glycosylation
  • Hemophilia A / genetics*
  • Humans
  • Molecular Weight
  • Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase
  • Thrombin / metabolism


  • Factor VIII
  • Thrombin
  • Amidohydrolases
  • Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase