Factor V Leiden
is the most common hereditary blood coagulation disorder in the United
States. It affects about 5% of the Caucasian population. The disease
is less common in Hispanics and African-Americans.
The cause of this disorder is a single nucleotide change (G to A at
position 1691) of the Factor V gene, referred to as the Factor V Leiden
mutation, resulting in a change in the protein sequence from an arginine
to a glutamine at position 506. The mutant protein cannot be inactivated
by activated protein C, which eventually leads to excess fibrin and
A 121 bp target fragment is amplified by isothermal Helicase
Dependent Amplification (HDA) using one common primer and two
allele specific primers: one for the wild type G (labeled with FI)
and the other for the mutant A (labeled with DIG).
After amplification, the reaction tube is placed in a Type
II BESt cassette for genotype determination. A Wild-type
allele (W) will show a visible T line and Mutant allele (M) will show
a colored C line (Figure 1). Both T and C lines will be visible for
a heterozygous genotype (H). It is invalid if no visible line is observed.