Each column keeps its native condition scope. Initial features are displayed alphabetically, not ranked by clinical importance. Counts remain separate, and an empty cell does not mean a feature cannot occur.
"},"coverage":{"countRecords":0,"emptyColumnKeys":[],"hpoRelease":"2026-06-23","narrativeSourceChanges":[],"records":4,"sourceGroups":{"omim":4,"orphanet":0,"published":0}},"features":[{"hpoId":"HP:0002625","label":"Deep venous thrombosis","primary":false},{"hpoId":"HP:0100724","label":"Hypercoagulability","primary":false},{"hpoId":"HP:0003645","label":"Prolonged partial thromboplastin time","primary":false},{"hpoId":"HP:0012175","label":"Resistance to activated protein C","primary":false}],"ledeHtml":"Factor V Leiden thrombophilia is an inherited disorder of blood clotting. Factor V Leiden is the name of a specific gene mutation that results in thrombophilia, which is an increased tendency to form abnormal blood clots that can block blood vessels.","mondoId":"MONDO:0008560","records":[{"frequencyKind":"reported","key":"399f82a87f5414c1362c740cad5ab17079e1c7151873388c85174c26821d7633","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:188055","disease_name":"Thrombophilia due to deficiency of activated protein C cofactor","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0002625","is_excluded":false,"label":"Deep venous thrombosis","onset_id":null,"reference":"OMIM:188055","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"50c28db339a46e10dcb2cada53d3051afbe46d8dc7a5f84e0d68ac2cdbd965be","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:188055","disease_name":"Thrombophilia due to deficiency of activated protein C cofactor","evidence":"IEA","frequency_raw":null,"hpo_id":"HP:0100724","is_excluded":false,"label":"Hypercoagulability","onset_id":null,"reference":"OMIM:188055","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"6115e4a4181b85e93dd061d89d2c8a0a7afe3f3ccbc50da5d59651b637a37dc3","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:188055","disease_name":"Thrombophilia due to deficiency of activated protein C cofactor","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0012175","is_excluded":false,"label":"Resistance to activated protein C","onset_id":null,"reference":"OMIM:188055","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"fac69784c8954045bc3d4a68f274ec3f4eafcb818611410cda757ffa0eaac6dc","raw":{"aspect":"P","body_system":"blood","disease_id":"OMIM:188055","disease_name":"Thrombophilia due to deficiency of activated protein C cofactor","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0003645","is_excluded":false,"label":"Prolonged partial thromboplastin time","onset_id":null,"reference":"OMIM:188055","source_release":"2026-06-23"},"sourceGroups":["omim"]}],"referenceLabels":{},"references":{"causeHtml":"","identityNote":"MONDO cross-references identify native condition entries. Ancestor membership does not transfer phenotype values between groups.","importantHtml":""},"sections":[{"bodyHtml":"A particular mutation in the F5 gene causes factor V Leiden thrombophilia. The F5 gene provides instructions for making a protein called coagulation factor V. This protein plays a critical role in the coagulation system, which is a series of chemical reactions that forms blood clots in response to injury.
The coagulation system is controlled by several proteins, including a protein called activated protein C (APC). APC normally inactivates coagulation factor V, which slows down the clotting process and prevents clots from growing too large. However, in people with factor V Leiden thrombophilia, coagulation factor V cannot be inactivated normally by APC. As a result, the clotting process remains active longer than usual, increasing the chance of developing abnormal blood clots.
Other factors also increase the risk of developing blood clots in people with factor V Leiden thrombophilia. These factors include increasing age, obesity, injury, surgery, smoking, pregnancy, and the use of estrogen for birth control (contraception) or to manage menopausal symptoms. The risk of abnormal clots is also much higher in people who have a combination of the factor V Leiden mutation and another mutation in the F5 gene. Additionally, the risk is increased in people who have the factor V Leiden mutation together with a mutation in another gene involved in the coagulation system.
","key":"forms","title":"What causes Factor V Leiden thrombophilia?"},{"bodyHtml":"People with factor V Leiden thrombophilia have a higher than average risk of developing a type of blood clot called a deep venous thrombosis (DVT). DVTs occur most often in the legs, although they can also occur in other parts of the body, including the brain, eyes, liver, and kidneys. Factor V Leiden thrombophilia also increases the risk that clots will break away from their original site and travel through the bloodstream. These clots can lodge in the lungs, where they are known as pulmonary emboli. Although factor V Leiden thrombophilia increases the risk of blood clots, only about 10 percent of individuals with the factor V Leiden mutation ever develop abnormal clots.
The factor V Leiden mutation is associated with a slightly increased risk of pregnancy loss (miscarriage). Women with this mutation are two to three times more likely to have multiple (recurrent) miscarriages or a pregnancy loss during the second or third trimester. Some research suggests that the factor V Leiden mutation may also increase the risk of other complications during pregnancy, including pregnancy-induced high blood pressure (preeclampsia), slow fetal growth, and early separation of the placenta from the uterine wall (placental abruption). However, the association between the factor V Leiden mutation and these complications has not been confirmed. Most women with factor V Leiden thrombophilia have normal pregnancies.
Source: MedlinePlus Genetics
","key":"overview","title":"Condition overview"}],"sharedSources":[],"slug":"factor-v-leiden-thrombophilia","sourceDocuments":[{"name":"Factor V Leiden thrombophilia","reviewed":"2023-08","sections":{"causes":{"fetchedAt":"2026-10-20T20:21:17.900691+00:00","label":"Causes","pageSha256":"6e9821aa5ef1a20aa4b3a6d5578417cd552fb10dc7b77fe05677f94fc616f8c6","sourceUrl":"https://medlineplus.gov/genetics/condition/factor-v-leiden-thrombophilia/#causes","status":"available"}},"source_release":"2026-10-01","url":"https://medlineplus.gov/genetics/condition/factor-v-leiden-thrombophilia"}],"sourceNote":"MedlinePlus descriptions and Causes; original HPO annotations.","takeawayHtml":"Cause explanations are from MedlinePlus Genetics. Feature values below retain their original sources and patient groups.","title":"Factor V Leiden thrombophilia"},"schemaVersion":1}