Factor V Leiden thrombophilia is a genetic disorder that makes it more likely for you to develop a blood clot sometime during your life.Still, it is estimated that 95% of people with factor V Leiden never develop a clot. When a clot does form, the clot most often occurs in your leg (deep venous thrombosis or DVT) or lungs (pulmonary embolism or PE).
https://rarediseases.info.nih.gov/diseases/6403/factor-v-leiden-thrombophilia