CPT® Code 81241

Molecular genetic testing is a critical procedure used to identify specific mutations within the F5 (coagulation Factor V) gene that are associated with hereditary hypercoagulability. The focus of this testing is on the Leiden variant, which is characterized by a particular mutation known as c.1601G>A or pArg534Gln. This mutation results in the inactivation of Factor V by activated Protein C (APC), a key component in the regulation of the clotting cascade. Factor V serves as a cofactor that facilitates the activation of Factor X, which subsequently activates thrombin. Thrombin plays a vital role in converting fibrinogen into fibrin, thereby forming a clot. However, when the F5 gene is mutated, Factor V remains in an active state, leading to an overproduction of thrombin and an excess of fibrin, which ultimately results in hypercoagulation or an increased tendency to form clots. The Leiden variant is classified as an autosomal dominant trait, meaning that the presence of just one mutated gene (heterozygous) can increase an individual's risk of developing venous thrombosis, particularly in the lower extremities. This variant is notably prevalent among the Eurasian population, with approximately 5% of Caucasians in North America carrying the heterozygous mutation and about 1 in 5000 individuals possessing the homozygous mutation. In cases of homozygous mutations, women may face heightened risks of venous thrombosis when using oral contraceptives, as well as an increased likelihood of adverse pregnancy outcomes such as miscarriage, stillbirth, fetal growth retardation, and placental abruption. Consequently, molecular genetic testing is recommended for women with a history of infertility or fetal loss, as well as for both men and women who have experienced deep vein thrombosis or pulmonary emboli.