Activated
Protein C Resistance
Clinical importance:
APC + PS complex neutralizes factors
Va and VIIIa preventing thrombosis
Mutation of gene responsible for
factor V synthesis results in a factor Va that is resistant to neutralization by APC + PS complex
Leiden – named after city in which
it was discovered
At the 506th amino acid glutamine is substituted for normal occurring arginine
Name &
Incidence of mutation:
Mutation:
The 506th amino acid is the site where APC + PS cleaves the factor Va molecule and
since glutamine is there instead of arginine the molecule is resistant to cleavage
5 – 10% of Northern European
caucasians have mutation
