A Case of Factor V Leiden Mutation Diagnosed After the Onset of DVT During Pregnancy in a Woman of Half-Japanese, Half-European Descent.

A 34-year-old pregnant woman of half-Japanese and half-European descent developed deep vein thrombosis at 23 weeks' gestation. Treatment included an initial infusion of unfractionated heparin, followed by subcutaneous injections, and oral edoxaban 60 mg after delivery. The patient's father had a history of venous thromboembolism and had been diagnosed with a Factor V Leiden mutation in Belgium. A subsequent genetic analysis revealed a heterozygous Factor V Leiden mutation, which was previously thought to be absent in Japan. In this era of globalization, the potential for genetic risk factors to cross geographical boundaries warrants careful consideration.