Abstract: Objective To investigate the correlation of genomic DNA methylation level with unexplained early spontaneous
abortion and analyze the role of DNMT1, DNMT3A and DNMT3B. Methods 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. Results 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). Conclusion 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.