OS086. Methylation status of the HOXA13 promoter region in placental tissue of pregnancies complicated by early onset severe preeclampsia.

Introduction: Compromised placental function and morphology found in early onset preeclampsia as well as a modified phenotype of the fetus may derive from a deviation in the normal gene expression pattern. Previous studies demonstrated by experimental animal models, that the gene HOXA13 plays an essential role in the arrangement of the placental vascular net, identifying direct and indirect target functions this gene has on the endothelial component. Research in model systems and now expanding to human studies has suggested that the causes and consequences of a variety of pregnancy-related pathologies are connected to epigenetic regulation.

Objectives: To evaluate the methylation status of the promoter region of HOXA13 within placental tissue and its association with specific clinical signs of severe early onset preeclampsia.

Methods: A prospective case - control study was performed to evaluate the methylation status of the promoter region of HOXA13 by pyrosequencing analysis within placental tissue and its association with specific clinical signs of severe early onset preeclampsia (EOSP).

Results: The group of preeclamptic patients reached a mean methylation degree of 27.06% (±8.94) and 30.56% (±8.08) on two CpG islands of HOXA13 5' promoter respectively. Conversely in the group of physiologic controls the mean degree of methylation resulted 15.12%(±3.64) (p<0.0016) and 18.25% (±3.45) (p<0.0005).

Conclusion: This study firstly demonstrated that an hypermethylation of placental HOXA13 exists in preeclamptic placental tissues and concentrates only on the gene promoter. Additionally, the existence of a correspondence between themethylation process of the gene promoter HOXA 13 and the clinical manifestation of severe early onset preeclampsia supports the original hypothesis that this process may be at the base of the preeclamptic pathogenesis.