Patient consent is required. To obtain consent form click here: Molecular Diagnostics Consent Form

UR Medicine Labs

Background Information for Factor V Leiden (F5) R506Q Mutation Characteristics: Factor V Leiden mutation is the most common cause of inherited thrombophilia and accounts for over 90% of activated protein C resistance. The expression of Factor V Leiden thrombophilia is impacted by coexisting genetic thrombophilic disorders, acquired thrombophilic disorders (malignancy, hyperhomocysteinemia, high factor VIII levels), and circumstances including: pregnancy, oral contraceptive use, hormone replacement therapy, selective estrogen receptor modulators, travel, central venous catheters, surgery, transplantation and advanced age. Incidence: Approximately 5% of Caucasians, 2% of Hispanics, 1% of African Americans and Native Americans and 0.5% of Asians are heterozygous; homozygosity occurs in 1 in 5000 individuals. Inheritance: Incomplete autosomal dominant. Penetrance: Lifetime risk of thrombosis is 10% for heterozygotes and 80% for homozygotes. Cause: A deleterious F5 gene mutation R506Q (1691G>A). Note: Standardized nomenclature for the Factor V Leiden mutation is c.1601G>A (p.Arg534Gln). Clinical Sensitivity and Specificity: 99%. Methodology: Polymerase chain reaction and fluorescence monitoring. Analytical Sensitivity and Specificity: 99%. Limitations: Rare diagnostic errors can occur due to primer site mutations. F5 gene mutations, other than R506Q, will not be detected.

Informed consent is required by NYSDOH for genetic testing. Consent forms are available online.