Prothrombin G20210A Mutation
Dr. T - I am 39 years old. I have a 16 year old son who was born at 24 weeks due to a placental abruption (he is perfectly fine today) and a 3, 2 and 1 year old from my current marriage. We wanted to have one more child and had 2 miscarriages this year. The 2nd miscarriage was at 15 weeks and my OB tested me and we found out I have Prothrombin G20210A gene mutation, a blood clotting disorder. I'm somewhat confused how my last 3 children were born with no problems other than I have an incompetent cervix. At my age, is this clotting disorder a high risk to my health/life? I would love to have another child, but I also REALLY want to be here for the 4 I have now. I'd love to hear your thoughts.
Kenneth F. Trofatter, Jr., MD, PhD said...
It is less likely the Prothrombin G20210A mutation had anything to do with your two miscarriages in view of your previous obstetrical history apart from the miscarriages. Much more common causes at your age are chromosomal abnormalities of the babies, an intrauterine abnormality such as a fibroid, scar tissue, or polyp, a hormonal abnormality such as thyroid disease, or an autoimmune condition. You have not told me the extent of your evaluation for “thrombophilias” that could contribute to your pregnancy losses, however, I am presuming you were at least screened for the more common genetic and acquired thrombophilias that have been variably linked to pregnancy loss and poor pregnancy outcome based on the fact you were identified as being a carrier of that prothrombin mutation.
About 2% of the population is heterozygous (carrying one dose) of the prothrombin mutation G20210A. This and the Factor V Leiden mutation are the two most common genetic causes of thrombophilia. Having the prothrombin mutation increases the risk of developing deep venous thrombosis (DVT), usually the result of a blood clot in the deep veins in the legs, and pulmonary embolus (PE) - a blood clot that travels to the lungs, usually from DVT - from approximately 1 in 1000 people to 2-3 in 1000 people each year. Having homozygous prothrombin mutations increases the risk even more. However, many people with the prothrombin mutation will never develop a blood clot in their lifetime. Factors that increase risk include age, pregnancy, obesity, family history of DVT/PE, smoking, diabetes, and the presence of other thrombophilias among many others.
So, those are my thoughts. The best thing you have going for you is the OB history of successful pregnancies in the past. If your doctor chooses to treat you during pregnancy to prevent venous thromboembolic events, at this point no more than prophylactic therapy is indicated. Good luck and thanks for writing.