RESUMO
<p><b>OBJECTIVE</b>To investigate the correlation of genomic DNA methylation level with unexplained early spontaneous abortion and analyze the role of DNMT1, DNMT3A and DNMT3B.</p><p><b>METHODS</b>Forty-five villus samples from spontaneous abortion cases (with 33 maternal peripheral blood samples) and 44 villus samples from induced abortion (with 34 maternal peripheral blood samples) were examined with high-pressure liquid chromatography (HPLC) to measure the overall methylation level of the genomic DNA. The expressions of DNMT mRNAs were detected using fluorescence quantitative-PCR in the villus samples from 33 induced abortion cases and 30 spontaneous abortion cases.</p><p><b>RESULTS</b>Genomic DNA methylation level was significantly lower in the villus in spontaneous abortion group than in induced abortion group (P<0.01), but similar in the maternal blood samples between the two groups (P>0.05). The mean mRNA expression levels of DNMT1 and DNMT3A in the villus were significantly lower in spontaneous abortion group than in induced abortion group (P<0.05), but DNMT3B expression showed no significant difference between them (P>0.05).</p><p><b>CONCLUSION</b>Insufficient genomic DNA methylation in the villus does exist in human early spontaneous abortion, and this insufficiency is probably associated with down-regulated expressions of DNMT1 and DNMT3A.</p>