Premature closure of foramen ovale and renal vein thrombosis in a stillborn twin homozygous for methylene tetrahydrofolate reductase gene polymorphism: a clinicopathologic case study.

Premature closure of the foramen ovale, 4-chamber cardiac hypertrophy, and renal vein/vena cava thrombosis were found at autopsy of a stillborn dizygotic twin at 36 weeks gestational age. Review of the original prenatal sonograms showed features suggestive of early closure of the foramen ovale. Homozygosity for the 5, 10 methylene tetrahydrofolate reductase mutation was shown only in the affected twin after the parents were found to be heterozygous for the mutation. The difference in outcome of the twins following prenatal treatment with beta mimetics and corticosteroids for preterm labor may be related to the added susceptibility factor for thromboembolism associated with presumed hyperhomocysteinemia in the proband which was not shared by the surviving healthy twin. The role of premature closure of the foramen ovale and prenatal treatment are discussed but remain uncertain.