Polymorphism for mutation of cytosine to thymine at location 677 in the methylenetetrahydrofolate reductase gene is associated with recurrent early fetal loss

OBJECTIVE: This study was undertaken to determine whether a cytosine to thy mine mutation at nucleotide 677 in the gene encoding for methylenetetrahydr ofolate reductase is associated with particular subtypes of recurrent unexp lained spontaneous abortion. STUDY DESIGN: The prevalences of cytosine to thymine mutation at nucleotide 677 in the gene encoding for methylenetetrahydrofolate reductase among 41 patients with recurrent unexplained spontaneous abortions and among 18 heal thy control subjects were determined with polymerase chain reaction. RESULTS: Homozygosity and heterozygosity for the cytosine to thymine mutati on at nucleotide 677 in the gene encoding for methylenetetrahydrofolate red uctase were observed at nonsignificantly different rates among patients and control subjects (9% and 48% versus 22% and 38%, respectively, P < .95). A mong patients with recurrent unexplained spontaneous abortions both homozyg osity and heterozygosity were associated with significantly increased preva lence of recurrent early fetal loss rather than with repeated anembryonic g estations (P < .0001). CONCLUSION: The observation that polymorphism for the cytosine to thymine m utation at nucleotide 677 in the gene encoding for methylenetetrahydrofolat e reductase is associated with repeated early fetal losses rather than with anembryonic gestations strengthens the argument for the role of hypercoagu lability and abnormal uteroplacental vasculature in recurrent spontaneous a bortion.