Factor V Leiden is a genetic blood clotting disorder caused by a mutation in one of the blood's clotting factors: the protein known as factor five, notes Nationwide Children's Hospital. Factor V Leiden increases clotting problems and abnormal blood clots, explains Mayo Clinic.
Most people with Factor V Leiden do not experience abnormal blood clots or any associated problems, according to Mayo Clinic. In some cases, small clots appear and resolve themselves without causing other symptoms.
Large, abnormal clots in key areas can cause significant damage and become fatal, reports Nationwide Children's Hospital. Factor V Leiden may cause blood clots in the lungs or brain, impairing breathing or nervous system functioning. People with Factor V Leiden mitigate clotting issues with the use of blood-thinning medications like Coumadin.