The level of methylation of LINE-1 retrotransposon in chorionic villi in embryos from families with sporadic and recurrent miscarriage

Background. Epigenetic processes such as DNA methylation play an important role in maintaining a normal pregnancy and their disruption may be associated with spontaneous abortion. Earlier, we found an increased level of methylation of the retrotransposon LINE-1, which makes up about 17% of the human genome, in the chorionic villi of spontaneous abortions.

Aim: to analyze the level of methylation of the LINE-1 retrotransposon in chorionic villi in embryos from families with sporadic and recurrent miscarriage.

Methods. The present study analyzes the differences in the level of methylation in chorionic villi of 46 induced abortions and spontaneous abortions from 155 families with sporadic miscarriage and 127 families with recurrent miscarriage. The methylation level of LINE-1 was assessed using targeted bisulfite massive parallel sequencing.

Results. No significant differences in LINE-1 methylation levels were found between the groups with recurrent and sporadic miscarriage (p>0.05). However, the LINE-1 methylation level was significantly higher compared to induced abortions (40.2 ± 2.2%) in spontaneous abortions with monosomy X from families with recurrent (42.0 ± 4.5%, p=0.04) and sporadic miscarriage (43.1 ± 5.2%, p=0.03), and in spontaneous abortions with trisomy 16 from families with sporadic miscarriage (43.1 ± 3.9%, p<0.001).

Conclusion. Abnormal methylation level of LINE-1 may be a marker of the death of part of the embryos in both sporadic and recurrent miscarriage.

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