Factor V Leiden is caused due to a mutation that results in a substitution at position 506 glutamine to which of the following:

Mutation in factor V (called the Leiden mutation, after the city in the Netherlands where it was discovered) causes recurrent DVTs. The mutation results in a glutamine to arginine substitution at position 506 that renders factor V resistant to cleavage by protein C. As a result, an impoant antithrombotic counter-regulatory pathway is lost Ref: Robbins 8th edition Chapter 4.