Factor V Leiden: An Overview

Extract

This paper provides an update and an overview of factor V Leiden, an inherited condition, which predisposes affected individuals to thrombosis. Factor V Leiden occurs due to a single point mutation on chromosome one. Tests for factor V Leiden include screening for activated protein C (APC) resistance, and if positive, testing for the Factor V Leiden mutation.

The human body maintains a delicate balance of procoagulant and anticoagulant processes by using a complex system of cofactors and inhibitors. The system uses a feedback mechanism to maintain the equilibrium.¹ When this balance is disrupted, there may be an episode of bleeding or a clotting event such as deep vein thrombosis (DVT) or pulmonary embolism (PE). Thrombophilia is used to describe the tendency of some people to form abnormal blood clots.² The consequences are usually DVTs of the legs, and PE, which can both cause considerable suffering and even death.¹ Each year, approximately 201,000 new cases of venous thrombosis are diagnosed in the United States. Of these, 107,000 individuals develop DVTs and 94,000 develop PE.³ Approximately 60,000 deaths in the United States each year are due to venous thromboembolism.³

Thrombophilia may be due to either an inherited condition or a condition that develops during life. Some examples of causes for development of non-hereditary thrombophilia are cancer, obesity, diabetes, and surgery.² Hereditary thrombosis, due to genetic mutations, is the cause of about half of the cases.¹ Causes for hereditary thrombophilia result from single gene mutations, and include protein C deficiency, protein S deficiency,…

ABBREVIATIONS: APC = activated protein C; APTT = activated partial thromboplastin time; DVT = deep vein thrombosis; INR = international normalized ratio; LMWH = low molecular weight heparin; MI = myocardial infarction; PCR = polymerase chain reaction; PE = pulmonary embolism.