George received this question on June 28, 2020, and has secured permission to post here while withholding the correspondent's identity.
Hello, and thank you for the Fritsma Factor. Our family is of Eastern Europe parentage and we have a genetic clotting family history. Several occurences have shown up at age 28 after a preceeding event. They have never been able to "pin it down" although some thought it was related to factor V. Thrombotic events killed my mother and aunt and my two brothers and I have all thrown PE 's. Now we have children who are experiencing thrombotic events. Any information you can provide to me would be appreciated.
Hello, and thank you for your interest in the Fritsma Factor. I am sorry for the thrombotic events you and your family have endured and for your family's losses. I hope you can "get to the bottom" of your condition and can prevent future events.
From your description, it appears that your family members possess a familial thrombosis risk factor. If you've not already done so, I recommend you get a referral to a hematologist who has expertise in hemostasis. The doctor will want to order a thrombosis risk profile for each family member, which usually includes phenotypic tests for antithrombin level, protein C, protein S, and activated protein C resistance and molecular tests for the factor V Leiden mutation and the prothrombin G20210A mutation. Some lab directors also include tests for elevated factor VIII activity levels. Most profiles also include an antiphospholipid syndrome series, including clot-based lupus anticoagulant testing, anti-cardiolipin antibody, and anti-beta-2 glycoprotein 1 enzyme immunoassays. The antiphospholipid syndrome, however, is an acquired, not inherited disorder.
The value of the profile is to identify your family's specific inherited risk factor and to pinpoint which family members have the condition. The therapeutic approach your hematologist is likely to employ is long term anticoagulation, probably using one of the post-2009 anticoagulant therapeutics such as Eliquis or Xarelto, both of which require minimal laboratory testing and possess desirable efficacy and safety profiles.
Again, thank you for your question and I encourage you to follow up if you have further questions or information.
In follow-up, the correspondent wrote, my nephew is on Eliquis, and my brother and I are both on Jantoven and have monthly protimes. I would assume that we would have to go off them to be tested, right?
George responds that, yes, for antithrombin, protein C, protein S, activated protein C resistance, and clot-based lupus anticoagulant tests, you would need to be off anticoagulants for at least 14 days. I DO NOT recommend this, as it would expose you to thrombosis risk. The factor V Leiden mutation assay [which provides the same information as the APCR ] and the prothrombin G20210A assay, plus the anti-cardiolipin antibody and anti-beta-2-glycoprotein 1 immunoassays are valid while you are on anticoagulants.
In the 1990s there was a push towards screening for all the thrombosis risk factors. Since about 2010, interest has waned because detecting an inherited risk factor doesn't necessarily change the therapy or outcome. Still, it seems a hemostasis-geared hematologist would like to profile your family to estimate your risks, identify the source and distribution of the risk factor, and confirm the need for long-term anticoagulation.
Again, thank you for your correspondence, and I wish you good health.